WILLIAM  CHAMBERS  COKER 


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THE 


SAPROLEGNIACEAE 

WITH 

NOTES  ON  OTHER  WATER  MOLDS 


BY 


WILLIAM  CHAMBERS  COKER 

KENAN  PROFESSOR  OF  BOTANY,  UNIVERSITY  OF  NORTH  CAROLINA 


WITH  SIXTY-THREE  PLATES 


Chapel  Hill,  N.  C.,  U.  S.  A. 

THE  UNIVERSITY  OF  NORTH  CAROLINA  PRESS 

1923 


Copyright,  1923,  by 

he  University  of  North  Carolina  Press 


Printed  by  the  Intelligencer  Press 
Lancaster,  Pa. 


INTRODUCTION 


C  INCE  the  appearance  about  thirty  years  ago  of  Humphrey’s  fine 
^  monograph  on  the  Saprolegniaceae  and  the  almost  simulta¬ 
neous  treatment  of  the  European  species  by  Fischer  in  Rabenhorst’s 
Flora,  there  has  been  much  work  done  on  the  water  molds,  both  in  this 
country  and  Europe.  A  number  of  new  species  have  been  described, 
fertilization  and  other  cytological  phenomena  investigated,  and  a  con¬ 
siderable  amount  of  experimenting  done  on  the  effect  of  various  media 
on  growth  and  reproduction.  It  has  been  my  purpose  to  get  together 
a  treatment  of  all  known  species  and  to  describe  and  illustrate  all 
species  I  have  seen  in  the  living  state.  Most  cytological  and  physiologi¬ 
cal  details  of  importance  appearing  in  the  literature  since  Humphrey’s 
work  have  been  included  or  referred  to  under  the  species  involved,  and 
I  have  not  thought  it  worth  while  to  write  a  long  introduction  covering 
these  points.  Researches  on  chondriosomes  and  our  own  work  on  the 
structure  and  behavior  of  the  emerging  spores  will,  however,  be  re¬ 
ferred  to  in  this  introduction. 

It  will  be  well  to  call  attention  first  to  several  conclusions  arrived 
at  by  Humphrey  that  have  since  been  shown  to  be  erroneous.  In  regard 
to  sexual  reproduction  Humphrey  decides  from  observations  by  himself 
and  others  that  fertilization  no  longer  occurs  in  the  Saprolegniaceae. 
This  we  now  know  to  be  incorrect.  A  true  sexual  fusion  occurs  in  Adilya 
americana  var.  cambrica,  A.  polyandra,  A.  deBaryana ,  Saprolegnia  monoica, 
S.  mixta ,  A.  diclina  and  Aphanomyces  laevis  (see  these  species  for  details), 
and  it  is  highly  probable  that  it  occurs  in  a  number  of  others  where 
antheridia  are  well  developed.  Credit  is  due  to  Trow  who  in  the  face 
of  much  criticism  carried  forward  to  a  convincing  conclusion  his  assertion 
of  sexuality  in  this  family. 

Humphrey  was  also  wrong  in  his  conclusion  (’92,  P-  77)>  contrary  to 
the  opinion  of  deBary,  Strasburger  and  Biisgen,  that  “  In  general,  there 
can  be  little  doubt  that  the  spores  of  the  genera  now  under  discussion 
[, Saprolegnia ,  Achlya ,  Aphanomyces]  leave  the  sporangia  automatically.” 
In  my  opinion  the  evidence  against  this  view  is  overwhelming.  In  the  first 
place,  in  genera  like  Achlya  and  Aphanomyces,  where  the  first  swimming 
stage  is  suppressed,  the  spores  certainly  have  no  ciliary  action  (even  where 
cilia  are  present)  sufficient  to  drive  the  spores  at  a  high  rate  of  speed  through 
an  opening  so  small  as  to  constrict  them.  \\  here  cilia  have  been  demon¬ 
strated  within  the  sporangium  their  action  is  very  feeble  and  spasmodic 


2 


THE  SAPROLEGNIACEAE 


and  leads  only  to  a  slight  rocking  or  jerking  motion.  Again,  the  spores 
move  as  a  mass  and  not  individually.  As  the  first  spores  escape  the 
others  draw  away  evenly  from  the  cell  wall  until  as  the  emptying  proceeds 
the  spores  form  an  axial  column  which  remains  solid  and  moves  toward 
the  opening,  the  spores  having  their  long  axes  all  parallel  to  the  long 
axis  of  the  sporangium.  The  spores  on  the  bottom  of  the  column  can  be 
plainly  seen  in  places  where  they  are  slightly  separated  and  it  is  per¬ 
fectly  obvious  that  if  any  ciliary  action  is  going  on  at  all  it  is  negligible 
as  a  motive  force.  Absolutely  conclusive  are  the  cases  where  large 
masses  of  protoplasm  are  ejected  from  a  sporangium  in  undifferentiated 
form,  the  entire  contents  at  times  plastically  pouring  out  of  the  small 
mouth  (see  page  9).  A  similar  case  is  the  ejection  of  the  bladders  from 
the  sporangia  of  Pythium ,  Rhipidium  and  Araiospora.  In  Aphanomyces 
the  main  bodies  of  the  elongated  spores  becomes  separated  by  an  ob¬ 
vious  interval  soon  after  the  sporangium  opens  (they  are  actually  connected 
by  a  slender  strand  of  protoplasm),  and  if  one  gets  caught  in  the  open¬ 
ing  all  the  others  in  the  row  stop  suddenly  and  start  forward  again  only 
when  the  obstruction  is  removed,  showing  that  the  spores  are  being  pass¬ 
ively  carried  forward  by  the  surrounding  medium.  In  Leptolegnia  the 
spores  emerge  with  force  but  do  not  swim  actively  away  as  would  be 
expected  if  this  force  were  continued.  They  slowly  move  about  at  the 
sporangium  mouth  reshaping  themseh’es  along  another  axis  preparatory 
to  active  swimming.  It  often  happens  in  Achlya  that  one  or  more  groups 
of  spores  on  emerging  become  separated  from  the  main  mass  by  some 
distance  (as  several  times  the  diameter  of  the  spores).  If  one  of  these 
masses  is  touched  all  the  groups  are  moved  or  jerked  by  the  impulse.  This 
shows  a  connecting  medium  less  fluid  than  water,  and  this  medium  we 
now  know  to  be  delicate  strands  of  protoplasm  (see  page  4). 

Just  what  causes  the  internal  pressure  that  drives  out  the  spores  has 
not  been  known  with  certainty.  There  is  a  shrinkage  in  the  size  of  the 
sporangium  during  the  discharge,  but  this  could  account  for  only  a  small 
part  of  the  result.  A  sporangium  of  Achlya  racemosa  measured  by  us 
was  2 1  [a  thick  before  and  18.7^  thick  after  the  discharge.  Aside  from 
this  there  would  seem  to  be  only  two  possible  alternatives,  the  simple 
absorption  of  water  due  to  higher  osmotic  tension  within,  or  the  swelling 
of  a  gelatinous  medium  by  absorption  of  water.  All  the  phenomena 
could  be  explained  by  the  assumption  that  the  expulsion  is  due  to  the 
swelling  of  a  peripheral  substance  inside  the  sporangium,  and  that  this 
is  the  cause  was  the  opinion  of  deBary,  as  clearly  expressed  in  his  Com¬ 
parative  Morphology  of  the  Fungi,  etc.,  p.  82.  The  only  difficulty  in  the 
way  of  the  acceptance  of  the  assumption  that  a  swelling  mucus  is  the 
cause  of  expulsion  is  the  entire  failure  so  far  of  all  efforts  to  demonstrate 


INTRODUCTION 


3 


the  presence  of  such  a  mucus  by  selective  stains.  Mr.  H.  R.  Totten, 
Instructor  in  this  laboratory,  has  carried  out  a  series  of  experiments  on  the 
emerging  spores  of  Achlya  and  has  used  various  stains  in  an  attempt  to 
determine  the  presence  of  a  mucus.  He  reports  as  follows:  “  I  have  been 
unable  to  demonstrate  the  presence  of  a  mucus  in  the  sporangium  while 
the  spores  are  moving  towards  the  central  axis,  or  about  the  escaping 
spores,  or  about  the  spherical  mass  of  spores  at  the  tip  of  the  sporangium 
after  their  escape.  The  following  stains  have  been  used:  Delafield’s 
Haematoxylin,  Methylene  Blue  following  Lead  Acetate  and  without  Lead 
Acetate,  Chloroiodide  of  Zinc,  India  Ink  after  growing  plants  in  i% 
Congo  red.”  On  account  of  the  even  distribution  of  pressure  through¬ 
out  the  sporangium,  which  would  follow  if  the  expellent  material  were 
simply  a  watery  sap,  the  grouping  of  the  spores  into  an  axillary  row 
while  emerging,  and  their  evident  attraction  to  each  other  would  have 
to  be  explained  on  the  assumption  that  they  actively  cling  and  press 
together.  Heretofore  no  explanation  has  been  offered  for  these  striking 
facts  except  the  very  unsatisfactory  suggestion  of  a  kind  of  liking  for 
each  other,  the  adelphotaxy  of  Hartog.  Humphrey  (p.  76)  favors  this 
explanation  and  also  asserts  the  opinion  that  there  is  no  material  con¬ 
nection  between  the  spores.  Realizing  the  unsatisfactory  state  of  this 
whole  matter,  we  have  been  carrying  on  recently  with  the  help  of  several 
of  our  students  an  examination  into  the  spore  discharge  in  Adilya, 
Aphanomyces  and  Leptolegnia,  and  we  are  now  prepared  to  add  some  new 
data  on  this  puzzling  subject. 

Rothert  (’88)  has  shown  that  the  spores  of  Adilya  polyandra  are 
connected  by  threads  on  emerging,  and  later  (’03)  found  that  the  same 
is  true  for  A phanomyces.  Mr.  J.  N.  Couch,  Instructor  in  this  laboratory,  has 
confirmed  these  observations  and  has  proved  that  there  is  a  material 
connection  between  the  spores  in  Achlya,  Aphanomyces  and  Leptolegnia 
while  in  the  sporangium,  and  that  in  the  first  two  this  connection  is  main¬ 
tained  until  the  spores  have  taken  their  position  in  the  apical  ball.  It 
is  our  opinion  that  these  connecting  strands  play  the  most  important 
part  in  drawing  the  spores  into  a  ball  in  Achlya  and  Aphanomyces  and 
in  holding  them  there.  This  remarkable  phenomenon  has  heretofore 
received  no  adequate  explanation.  Rothert  thinks  the  spores  are  held 
together  in  a  ball  by  a  gum  but  as  said  above  we  find  no  such  substance. 
In  his  first  treatment  of  the  genus  Aphanomyces,  deBary  demonstrated 
the  presence  of  a  slender  filament  of  protoplasm  connecting  the  emerging 
spores  in  the  sporangium  (’60,  pi.  19,  fig.  3),  but  he  said  that  at  times 
they  were  without  this  connection.  In  our  experience,  when  this  con¬ 
nection  is  absent  it  is  evidence  that  the  sporangium  will  not  empty  and 
that  the  spores  have  reorganized  themselves  for  a  rest. 


4 


THE  SAPROLEGXIACEAE 


In  Leptolegnia,  Petersen  (Ann.  Myc.  8:  522.  1910)  found  that  the 
spores  were  linked  together  by  their  cilia  on  passing  through  the  sporangium. 
Mr.  Couch  finds  that  the  cilia  are  formed  from  the  original  protoplasmic 
layers  connecting  the  spore  origins  while  they  are  against  the  cell  wall, 
that  these  threads  unless  jerked  apart  by  a  too  vigorous  rocking  of  the 
spores  persist  and  thus  the  spores  as  they  emerge  are  connected  with 
four  protoplasmic  threads,  two  in  front  and  two  behind.  After  emerging 
from  the  sporangium  two  of  these  four  connections  persist  as  cilia,  but 
which  two  has  not  yet  been  clearly  demonstrated. 

In  the  case  of  Achlya ,  Mr.  Couch  finds  a  similar  condition.  A 
sporangium  of  Achlya  dubia  in  the  act  of  discharging  its  spores  was 
killed  with  1%  osmic  acid,  and  the  discharged  spores  instead  of  forming 
a  close  mass  at  the  tip  of  the  sporangium  separated  a  short  distance 
from  each  other  but  remained  attached  in  a  loose  cluster  to  the  tip  of  the 
sporangium  as  if  held  together  by  a  mucus  or  by  delicate  threads  of 
protoplasm.  At  this  moment  the  sporangium  was  dragged  gently  by 
the  observer  for  a  distance  of  several  millimeters.  At  first  the  entire 
mass  moved,  and  then  the  spores  began  stringing  out,  the  ones  behind 
being  pulled  apparently  by  those  in  front.  A  cover  glass  was  then 
applied  and  the  spores  stained  with  a  1%  solution  of  Fuchsin  and  methyl 
violet  in  95%  alcohol,  to  which  was  added  three  times  its  volume  of 
water.  This  stain  brought  out  unmistakable  connections  of  delicate 
protoplasmic  threads  between  the  spores.  Many  spores  had  become 
separated  from  the  general  mass  and  it  was  observed  that  these  connect¬ 
ing  protoplasmic  threads  were  on  both  ends  of  some  spores,  while  on  other 
spores  the  threads  were  in  the  normal  position  for  cilia.  Furthermore, 
spores  on  which  these  threads  occupied  all  intermediate  positions  between 
the  above  two  were  observed.  Similar  results  were  obtained  with  A.  con- 
spicua,  A.  apiculata  and  its  variety  prolifica,  A.  Orion,  and  A.  flagella ta. 
Mr.  Couch’s  work  on  this  problem  is  still  in  progress  and  will  be  published 
with  illustrations  in  a  future  number  of  the  Journal  of  the  Elisha  Mitchell 
Scientific  Society. 

In  discussing  the  peculiar  behavior  of  the  spores  in  Achlya  paradoxa 
(now  Protoachlya)  I  gave  some  years  ago  (’14,  p.  294)  a  short  review 
of  the  variations  from  the  supposed  normal  behavior  of  the  sporangia 
and  spores  in  the  Saprolegniaceae,  as  recorded  in  the  literature.  As 
rather  numerous  records  have  appeared  since  1914,  I  think  it  worth 
while  to  reprint  this  review  with  such  additions  and  changes  as  are 
needed  to  bring  it  up  to  date. 

In  the  case  of  Achlya  a  departure  from  or  modification  of  the  usual 
grouping  of  the  spores  at  the  sporangium  tip  has  been  recorded  in  a  few 
instances.  In  the  first  place  it  must  be  remembered  that  the  spores  in 


INTRODUCTION 


5 


this  genus  are  not  perfectly  quiescent  during  and  immediately  after 
emergence.  A  slight  amoeboid  motion  is  observable  at  all  times  from 
their  initial  formation  to  the  appearance  of  the  encysting  membrane. 
Added  to  this  is  a  certain  feeble  jerking  and  rotation  due  to  the  presence 
of  cilia  that  has  been  recorded  by  several  observers  since  Cornu  first 
described  it  in  1872.  On  page  n  of  his  monograph  Cornu  says  that 
these  cilia  have  just  enough  agility  to  cause  the  escape  of  the  spores 
from  the  sporangium,  thus  implying,  in  error,  that  they  are  the  cause 
of  the  escape.  The  presence  of  cilia  on  the  emerging  spores  of  Achlya  is 
strongly  asserted  by  Hartog  (’87)  who  also  predicts  that  they  will  be 
found  in  all  species  of  Adilya  and  Aplianomyces  (’88). 

Hartog  also  says  in  the  first  of  these  papers  that  the  spores  of  Adilya 
after  forming  a  ball  revolve  on  their  long  axes  for  a  short  time  before 
the  cyst  is  formed,  and  that  sometimes  a  few  spores  will  detach  them¬ 
selves  and  swim  away  a  short  distance.  In  the  second  paper  he  says: 
“When  the  sporange  is  discharged  near  the  margin  of  the  hanging  drop 
or  in  a  thin  layer  of  water  on  a  slide,  we  constantly  see  single  spores  escape 
from  the  mass,  swim  away,  and  encyst  apart.”  This  important  obser¬ 
vation  has  been  frequently  overlooked  by  subsequent  workers,  but  I 
can  confirm  it  positively  for  Adilya  caroliniana.  In  this  case  if  the  spor¬ 
angium  is  put  on  the  slide  in  a  very  thin  layer  of  water  the  spores  will 
swim  slowly  apart  on  emerging  and  scatter  themselves  over  a  limited 
area  near  the  mouth  of  the  sporangium.  By  addition  of  iodine  solution 
the  cilia  were  clearly  seen.  In  the  case  of  Adilya  deBaryana  I  have  ( ’  1 1 ) 
recorded  the  occasional  breaking  up  of  the  spore  mass  into  scattered  groups 
and  the  same  habit  I  have  often  observed  in  A.  racemosa,  A.  colorata, 
and  A.  hypogyna ,  and  in  the  last  the  spores  are  ciliated  on  emerging. 
Humphrey  in  his  monograph  also  demonstrated  the  presence  of  cilia  on 
the  escaping  spores  of  Adilya  americana,  and  says,  “In  A.  polyandra  one 
can  hardly  fail  to  notice  the  very  marked  ciliary  motion  within  the  sporan¬ 
gium  during  the  escape  of  the  spores.”  It  will  be  noted,  however,  that  in 
none  of  these  cases  do  any  of  the  spores  swim  away  regularly  and  under 
ordinary  circumstances  when  first  discharged. 

In  case  of  bacterial  contamination,  or  foulness  from  any  cause,  or 
where  the  parts  are  put  in  liquid  nutrient  media,  there  is  a  strong  tendency 
for  the  spores  to  be  retained  in  the  sporangium,  or  if  discharged  for  them 
to  sprout  at  once  without  a  second  swimming  stage.  There  has  arisen 
a  loose  way  of  speaking  of  all  sporangia  when  the  spores  are  retained,  or 
even  in  part  retained,  as  dictiosporangia,a  term  that  should  be  used 
only  when  spores  emerge  singly  through  the  wall  of  the  sporangium  and 
escape  for  (what  is  homologous  with)  the  second  swimming  stage.  As 
one  might  expect,  there  is  variation  in  Dictyuchus  itself  in  this  respect, 


6 


THE  SAPROLEGNIACEAE 


the  spores  frequently  sprouting  by  the  Aplanes  method  (see  below). 
Variations  in  the  discharge  and  behavior  of  the  spores  are  recorded  in 
the  following  cases  (many  others  are  recorded  under  the  species  in  this 
book) : 

Adilya  aplanes  Maurizio  (’94).  The  behavior  of  the  spores  as  described 
in  this  case  is  very  peculiar.  There  is  no  swimming  stage,  the  spores 
on  emerging  sprouting  into  tubes.  Frequently  they  do  not  emerge 
at  all,  but  remain  in  the  sporangium  and  sprout  there.  (That  these 
statements  hold  true  regularly  under  normal  conditions  must,  I 
think,  remain  doubtful  until  the  plant  is  studied  by  some  one  else). 
Adilya  caroliniana  Coker  (To).  The  spores  may  be  retained  and  sprout 
as  in  Aplanes,  or  under  certain  circumstances  may  emerge  in  a  motile 
condition.  They  may  also  emerge  from  several  mouths.  Later 
observation  by  me  shows  that  under  certain  conditions  as  on  egg 
yolk  in  1  per  cent  KN2P04  the  spores  may  not  stick  to  the  sporan¬ 
gium  mouth,  but  fall  to  the  bottom  in  open  order.  This  is  true 
also  of  A.  flagellata  (see  our  treatment). 

Adilya  deBaryana  Humphrey  ( Adilya  polyandra  deBary) :  Coker  (’12). 
Figs.  7  and  8,  of  plate  78,  show  reduced  sporangia  with  spores  in 
a  single  row,  the  spores  emerging  exactly  as  in  Dictyuchus.  They 
also  frequently  sprout  as  in  Aplanes. 

Achlya  glomerata  Coker  (’12a).  In  fig.  7,  plate  79,  is  shown  a  sporangium 
with  the  spores  sprouting  as  in  Aplanes. 

Achlya  polyandra  Hildebrand:  Ward  (’83).  In  plate  22,  fig.  8,  is  shown 
a  sporangium  with  the  spores  emerging  just  as  in  Dictyuchus.  The 
retention  of  the  spores  in  this  case  he  was  able  to  bring  about  by 
poor  aeration,  i.e.,  placing  the  culture  in  an  air-tight  chamber. 
Achlya  prolifera  (Nees)  deBary  (’52).  In  plate  7,  fig.  28,  is  shown  the 
sprouting  of  the  spores  at  the  mouth  of  the  sporangium,  the  second 
swimming  stage  omitted.  In  all  the  species  of  Achlya  that  I  have 
studied  the  second  swimming  stage  may  be  easily  suppressed. 
Achlya  racemosa  Hildebrand:  Pringsheim  (’73)-  In  plate  22,  figs.  1,  2, 
and  3,  are  shown  sporangia  emptying  exactly  as  in  Dictyuchus. 
Linder  the  name  of  Achlya  lignicola,  which  I  am  treating  as  a  variety 
of  A.  racemosa,  Hildebrand  figures  a  sporangium  with  many  of  the 
spores  remaining  undischarged  (’67,  pi.  16,  fig.  2).  In  both  A. 
racemosa  and  A.  colorata  the  emptying  spores  hang  together  im¬ 
perfectly  and  often  separate  into  several  groups. 

Achlya  duhia  Coker  (see  p.  135).  In  this  species  the  sporangia  discharge 
their  spores  in  part  as  in  Achlya  and  in  part  as  in  Thrausto theca; 
also  not  rarely  as  in  Dictyuchus . 


INTRODUCTION 


7 


We  have  found  in  Achlya  caroliniana,  A.  proliferoides,  A  flagellata 
and  A.  Klebsiana  that  sporangia  may  open  and  discharge  spores 
through  more  than  one  papilla.  This  tendency  is  most  distinctly 
shown  in  the  last  species,  which  see  for  other  peculiarities  in 
above  behavior. 

Adilya,  hypogyna.  Spores  ciliated  on  emergence  and  may  show  a  sluggish 
motion.  .See  p.  102. 

Protoachlya  and  Isoachlya.  For  the  behavior  of  the  spores  and  spor¬ 
angia  in  these  genera,  see  our  treatment. 

Thraustotheca  davata  (deBary)  Humphrey:  Weston  ( T 8,  pi.  4,  fig.  31) 
shows  the  spores  sprouting  as  in  A  planes. 

Dictyuchus  monosporus  Leitgeb  (’69).  In  plate  23,  fig.  8,  Leitgeb  shows 
a  sporangium  with  spores  sprouting  after  the  manner  of  Aplanes. 
This  variation  I  have  many  times  seen  in  Dictyuchus  sterile ,  which 
is  common  at  Chapel  Hill  (pi.  52,  fig.  4).  Weston  (’19,  pi.  23,  fig. 
18)  shows  a  similar  case  in  a  sterile  Dictyuchus.  He  also  finds  that 
a  spore  may  in  some  cases  emerge  from  its  cyst  in  the  same  form  and 
swim  again  (“repeated  emergence”). 

Aplanes  androgynus  (Archer)  Humphrey.  See  our  discussion  of  this  spe¬ 
cies. 

Aphanoniyces  stellatus  deBary:  Sorokine  (’76).  In  plate  7,  figs.  10  and 
18,  are  shown  sporangia  discharging  their  spores  in  the  exact  manner 
of  Dictyuchus.  Sorokine  also  shows  sprouting  at  the  mouth  of  the 
sporangium,  and  sporangia  with  spores  in  more  than  one  row.  See 
also  Humphrey  (’92,  p.  79)  for  omission  of  second  swimming  stage. 
We  find  that  spores  retained  in  the  sporangium  may  sprout  as  in 
Aplanes. 

Leptomitus  lacteus  (Roth)  Agardh:  Humphrey  (’9 2)  says  on  p.  136: 
“While  the  zoospores  ordinarily  escape  from  the  sporangia,  they 
sometimes  become  encysted  within  them  (fig.  1 1 7) .  It  is  this 
fact,  probably,  which  led  Braun  to  state  (’51)  that  the  spores  of 
Leptomitus  are  arranged  in  a  row  in  the  spore  cases,  and  that  no 
active  gonidia  seem  to  occur.”  We  have  often  seen  some  of  the 
spores  retained. 

A podachlya  pyrifera  Zopf  (’88).  The  spores  normally  encyst  at  the 
mouth  of  the  sporangium  and  then  emerge  for  a  swimming  stage  as 
in  Achlya.  However,  they  may,  on  occasion,  swim  away  in  emerg- 
,  ing,  or  they  may  encyst  in  part  in  the  sporangium.  In  our  form  of 
the  species  it  is  much  more  usual  for  the  spores  to  swim  at  once  on 
emergence. 

Monoblepharis  macrandra  Woronin  (’04).  In  this  species  some  or  all 
of  the  spores  may  be  retained  in  the  sporangium  and  sprout  there. 
Normally  the  spores  on  emerging  show  amoeboid  movements. 


8 


THE  SAPROLEGNIACEAE 


Saprolegnia  asterophora  deBary  (’60).  Tn  plate  20,  tig.  25,  deBary 
shows  a  partly  emptied  sporangium,  the  remaining  spores  sprouting 
into  tubes. 

Saprolegnia  ferax  (Gruith.)  Thuret  (’50).  In  plate  22,  tig.  8,  Thuret 
shows  an  unopened  sporangium  with  the  spores  sprouting  in  posi¬ 
tion.  This  is  a  good  example  of  the  Apiaries  method.  In  this 
species  Pringsheim  (’73)  gives  an  interesting  case  (tig.  12,  plate 
21)  of  the  contents  of  an  egg  turning  immediately  into  a  sporangium 
the  spores  being  retained  and  sprouting  in  position.  In  figs,  ia,  b, 
c,  plate  20,  he  shows  spores  that  had  been  retained  in  a  partly  dis¬ 
charged  sporangium.  These  had  sprouted  in  position  to  short  tubes 
which  became  sporangia  and  discharged  small  spores. 

In  the  case  of  a  parasite  on  fish  that  he  considers  Saprolegnia 
ferax,  Smith  (’78)  gives  a  figure  showing  spores  sprouting  inside 
the  sporangium  at  one  end  while  others  are  swimming  out  at  the 
other.  Such  a  combination  is  probably  fanciful. 

Saprolegnia  monoica  Pringsheim:  Huxley  (’82)  describes  the  regular 
occurrence  towards  the  end  of  active  growth  of  sporangia  of  the 
Aplanes  type.  He  calls  them,  improperly,  “dictiosporangia.  ”  In 
this  plant,  which  was  a  parasite  on  salmon,  it  is  noteworthy  that 
Huxley  found  no  motion  in  the  spores  but  only  a  passive  drifting 
about  when  discharged.  In  a  similar  (probably  the  same)  plant, 
found  as  a  parasite  on  fish,  Unger  (’44)  gives  a  figure  (fig.  11,  plate 
1)  showing  a  few  spores  left  in  the  sporangium  and  sprouting  there 
into  long  tubes.  In  this  parasite  he  records  the  spores  as  swimming 
on  leaving  the  sporangium,  not  floating  away  as  in  Huxley’s  plant. 

Saprolegnia  torulosa  deBary:  Lechmere  (To)  illustrates  in  fig.  33,  plate 
2,  a  sporangium  with  spores  sprouting  after  the  manner  of  Aplanes. 
He  later  gives  (Ti,  fig.  2)  another  example.  In  his  first  paper  he 
shows  that  the  second  swimming  stage  may  be  suppressed.  DeBary 
(’84,  p.  1 1 7)  says  that  the  second  swimming  stage  may  be  omitted 
in  any  species  of  Saprolegnia,  and  this  we  can  confirm  for  the  species 
studied. 

Saprolegnia  furcata  Maurizio  (’99).  The  spores  are  frequently  retained 
and  sprout  as  in  Aplanes. 

Saprolegnia  sp.?:  Pringsheim  (’60).  In  plate  22,  fig.  9,  is  shown  a 
sporangium  emptying  as  in  Dictyuchus.  It  is  attached  to  a  hypha 
which  also  bears  a  sporangium  of  the  normal  Saprolegnia  type. 
Miss  Collins  (’20,  figs.  3-1 1)  also  illustrates  sporangia  of  both  the 
Dictyuchus  and  Aplanes  types,  or  the  two  combined,  in  a  sterile 
species  of  Saprolegnia. 


INTRODUCTION 


9 


In  both  Saprolegnia  and  Achlya  it  frequently  happens  that  the 
discharge  of  the  spores  is  only  partial,  a  few,  or  even  a  good  many  spores 
being  left  in  the  sporangium.  These  retained  spores  may  emerge  from 
their  cysts,  as  normally,  for  a  second  swimming  stage,  moving  about 
within  the  sporangium  until  they  find  their  way  out  by  its  mouth,  if 
they  ever  do.  This  is  shown  by  Hildebrand  ( ’67)  for  his  Achlya  polyandra , 
by  Lechmere  (To)  for  Saprolegnia  torulosa  (?),  plates  1  and  2,  figs.  22, 
23,  3°>  3C  also  in  fig.  2  of  his  1911  paper,  and  very  strikingly  in  our  form 
of  A.  Klebsiana  (which  see).  Lechmere  erroneously  calls  this  the  Dicty- 
uchus  type  of  asexual  reproduction.  It  is  doubtful  if  the  sterile  species 
of  Saprolegnia  (a  parasite  on  fish)  studied  by  him  in  his  first  paper  is 
Saprolegnia  torulosa.  It  is  more  apt  to  be  our  S.  parasitica. 

Another  peculiar  and  rare  variation  in  the  behavior  of  the  sporangial 
contents  is  described  and  figured  by  Horn  (’04)  in  a  plant  he  calls  Achlya 
polyandra  deBary  (which  may  be  our  A.  imperfecta) .  At  a  temperature  of 
31 0  to  320  Celsius,  sporangia  were  formed  which  emptied  large  masses 
of  protoplasm  through  several  openings.  These  masses,  then,  by  direct 
division  formed  spores,  some  of  usual  size  (iO[x),  some  larger  (up  to  40;j. 
in  diameter).  If  now  brought  to  room  temperature  these  small  spores  es¬ 
caped  from  their  cysts  and  swam.  The  larger  ones  germinated  directly. 
Horn  also  mentions  the  occasional  appearance  of  double  spores  from  nor¬ 
mal  sporangia.  The  discharge  of  large  and  irregular  masses  of  protoplasm 
from  the  sporangia  had  been  figured  long  ago  by  Leitgeb  (’69),  for 
Saprolegnia  monoica  as  Di planes.  In  plate  24,  fig.  5  he  shows  several 
such  masses,  some  with  cilia  at  different  points,  also  several  double 
zoospores.  In  Achlya  imperfecta  from  Chapel  Hill,  I  have  observed 
several  times  the  emptying  of  the  entire  protoplasm  from  a  sporangium 
at  the  tip,  the  mass  falling  at  once  to  the  bottom  as  a  long  contorted 
rope.  This  is  conclusive  evidence  that  the  spores  are  discharged  by 
internal  pressure  and  not  through  their  own  motion.  In  numerous 
other  species  I  have  seen  masses  of  protoplasm  much  larger  than  spores 
discharged  from  the  sporangium  and  these  may  have  several  sets  of  cilia 
(pi.  1,  fig.  12;  pi.  7,  fig.  1;  pi.  39,  fig.  4;  pl-  60,  figs.  12  and  14). 

It  will,  of  course,  be  understood  that  the  variations  reviewed  above 
are  in  no  sense  fortuitous  or  accidental.  I  hey  are  the  results  of  en¬ 
vironmental  conditions  and  many  of  them  may  now  be  induced  at  will 
by  the  investigator. 

In  this  connection  I  feel  it  necessary  to  give  a  word  of  caution  against 
the  attitude  adopted  by  Lechmere  in  his  two  papers  in  the  New  Phytol- 
ogist,  both  of  which  are  referred  to  above.  In  the  summary  of  his  first 
paper  he  says:  u  As  the  result  of  keeping  a  species  ol  Saprolegnia  under 


10 


THE  SAPROLEGNIACEAE 


observation  for  a  period  of  five  months  it  has  been  found  possible 
to  obtain  on  the  same  mycelium  the  methods  of  asexual  reproduction 
which  are  characteristic  of  six  different  genera.”  If  this  claim  is  ex¬ 
amined  it  will  be  seen  that  outside  of  its  own  genus  ( Saprolegnia )  the 
species  he  describes  cannot  with  accuracy  be  said  to  show  the  methods 
of  asexual  reproduction  of  any  other  genera  except  Aplanes  and  Lepto- 
legnia,  and  even  in  these  cases  only  in  certain  details,  not  in  all.  The 
sporangial  variations  cited  do  not  look  like  the  sporangia  of  the  genera 
in  question  and  neither  do  the  spores  within  them,  and  no  one  familiar 
with  these  genera  would  be  misled  into  placing  them  there  unless  one’s 
attention  be  focused  on  the  wording  of  keys  rather  than  on  the  plants 
themselves.  Such  variations  as  these  do  not,  as  Lechmere  implies,  create 
doubt  of  the  validity  of  the  presently  accepted  classification  of  the 
Saprolegniaceae. 

The  egg  structure  falls  into  two  main  types.  In  all  cases  the  fatty 
reserve  is  on  or  near  the  periphery,  but  in  one  type  it  is  in  the  form 
of  small  droplets  entirely  surrounding  the  protoplasm,  while  in  the  other 
it  is  collected  into  one  or  a  few  larger  drops  on  one  side.  The  first  of  these 
types  is  called  centric,  the  second  eccentric,  but  intergrading  types  occur 
which  connect  the  two  extremes,  and  for  certain  of  these  I  have  found  it 
useful  to  introduce  the  word  subcentric.  The  three  terms  may  be  de¬ 
fined  as  follows: 

A  centric  egg  has  one  or  two  layers  of  small  fat  droplets  entirely 
surrounding  the  central  protoplasm. 

A  subcentric  egg  has  the  protoplasm  surrounded  by  one  layer  of 
droplets  on  one  side  and  two  or  three  layers  on  the  other,  or  rarely  with 
the  droplets  entirely  lacking  on  part  of  one  side  as  in  Achlya  oblongata ; 
this  last  condition  connecting  directly  with  such  eccentric  structure  as 
is  shown  by  Pythiopsis  cymosa. 

An  eccentric  egg  has  one  large  drop  on  one  side  either  outside  the 
protoplasmic  surface  or  barely  enclosed  by  a  thin  layer  of  protoplasm, 
or  several  large  drops  enclosed  in  the  protoplasm  on  one  side,  or  a  lunate 
row  of  small  drops  (in  optical  sections)  on  one  side,  as  in  Pythiopsis  cymosa. 

The  egg  structure  is  of  much  systematic  significance.  It  is  always  the 
same  in  a  given  species  and  is  often  the  same  throughout  an  accepted 
genus,  or  else  in  groups  of  obviously  related  species  within  a  genus. 

Since  Humphrey’s  review  of  the  cytology  of  spore  formation  there 
is  nothing  of  importance  to  add,  except  the  work  by  Rothert  referred  to 
above  and  the  careful  study  by  Weston  of  the  exact  shape  of  the  spores 
in  Achlya  (’17),  Thraustotheca  (T8)  and  Dictyuchus  (’19).  The  cytology 


INTRODUCTION 


1 1 

of  the  vegetative  threads  of  Saprolegnia  and  Adilya  has,  on  the  other 
hand,  received  considerable  attention  from  Dangeard  (’16),  Meyer  (’04), 
Randolph  (’12)  and  Guilliermond  (’20,  Gob).  These  authors  find  this 
material  excellent  for  the  study  of  the  minute  bodies  known  as  chon- 
driosomes  (chondriomes,  chondriokonts,  mitochondria).  The  last  named 
author  has  also  studied  carefully  the  origin  of  the  vacuoles  in  Saprolegnia 
and  as  he  has  given  much  attention  to  these  subjects  in  a  number  of  well 
balanced  studies  it  will  be  of  interest  to  give  some  of  his  conclusions  in  a 
recent  summary  of  his  results  (’20),  as  follows  (translated  and  adapted): 

“With  the  help  of  vital  stains  one  may  see  that  in  very  young  fila¬ 
ments  the  system  of  vacuoles  is  composed  of  long  little  canals  that 
anastomose  in  a  network  which  by  swelling  and  fusion  finally  form  a 
large  vacuole,  a  sort  of  large  canal  occupying  the  whole  axis  of  the  fila¬ 
ment.  The  little  canals  and  the  network  are  filled  with  a  substance  in 
solution  that  stains  quite  strongly.  When  the  central  canal  is  formed 
this  substance,  being  more  diluted,  stains  in  a  much  paler  manner.  The 
systbm  of  vacuoles  also  contains,  except  in  the  initial  stages,  bodies  that 
stain  in  a  more  marked  manner  than  the  substance  dissolved  in  the 
vacuolary  sap.  Some  show  only  after  vital  staining;  they  are  strongly 
stained  and  in  a  very  metachromatic  manner.  The  others  appear  in 
the  form  of  corpuscles,  often  quite  large,  with  a  refraction  quite  marked 
and  visible  without  staining.  Osmic  acid  gives  them  a  slightly  gray 
tint.  The  vital  stains  color  them  only  feebly.  After  fixing  in  alcohol 
or  formalin  and  staining  with  methyl  blue  the  system  of  vacuoles  does 
not  show  the  characters  shown  in  the  living  state.  The  vacuoles  are 
uncolored  except  for  only  little  grains,  some  strongly  colored  with  deep 
violet  and  others  tinted  with  pale  blue.  Haematoxylin  does  not  color 
the  first  and  gives  to  the  second  a  diffuse  tint.  These  two  groups  of 
corpuscles,  which  are  perhaps  only  different  states  of  the  same  substance, 
do  not  show  the  characters  of  the  granules  drawn  in  the  fungi  under 
the  name  of  metachromatic  bodies. 

“The  employment  of  appropriate  methods  allows  one  to  obtain 
excellent  differentiation  of  the  chondriosome  which  appears  in  the  same 
manner  that  it  showed  when  living.  These  methods  do  not  stain  the 
contents  of  the  system  of  vacuoles  except  in  exceptional  cases,  when 
the  preparation  has  turned  out  badly.  I  he  fixations  of  commercial 
formalin  followed  by  staining  with  iron  haematoxylin  put  in  evidence 
with  the  greatest  clearness  the  nuclei  and  the  chondriosomes.  The 
methods  of  Benda  and  of  Kull  differentiate  also  the  fatty  granules  which 
appear  brown  with  osmic  acid.  W  ith  all  these  methods  the  chondriosome 
appears  to  be  made  up  of  numerous  particles  (chondriokonts)  of  vari¬ 
able  length,  which  are  differentiated  very  clearly  by  their  intense  colora- 


12 


THE  SAPROLEGNIACEAE 


tion  from  the  cytoplasm  of  very  little  color.  These  elements  have  a 
form  so  clear  that  it  is  sometimes  difficult  to  distinguish  them  from 
bacteria  that  are  sometimes  found  collected  on  the  wall  of  the  fungus. 
In  certain  filaments  these  chondriokonts  undergo  certain  modifications 
of  form  which  also  show  in  the  living  material;  they  can  take  the  form 
of  short,  thick-set  clubs,  of  spindles,  and  even  be  transformed  into 
vesicles.  It  is  difficult  to  decide  whether  these  forms  are  in  relation 
to  the  cellular  metabolism  or  represent  alterations  of  the  chondriosomes. 
The  chondriosomes  show  a  greater  resistance  to  the  fixatives  containing 
acetic  acid  than  similar  bodies  in  general  and  than  those  of  the  other 
fungi  in  particular.”  To  summarize,  Guilliermond  finds  in  the  Saprolegnia 
studied:  ist,  chondriosomes  quite  characteristic  and  comparable  to  those 
of  the  other  plants  and  animals;  2nd,  little  fatty  globules;  3rd,  a  system 
of  vacuoles  filled  with  a  substance  endowed  with  selective  power  against 
the  vital  stains,  but  which  has  not  the  characters  of  metachromatine. 

Aside  from  the  dates  and  places  of  collection  given  incidentally  and 
usually  in  meager  numbers  by  systematic  writers,  little  is  known  of  the 
occurrence,  periodicity  and  environmental  factors  involved  in  the  growth 
of  the  Saprolegniaceae.  The  one  paper  of  importance  dealing  with  these 
subjects  is  by  Petersen  in  his  treatment  of  the  Danish  water  molds  (To, 
p.  504).  His  valuable  notes  are  in  most  cases  in  agreement  with  our 
experience.  Certain  differences  are  found  and  to  be  expected,  due  to 
the  cold  climate  of  Denmark,  as  that  the  period  of  the  Saprolegniaceae 
begins  in  the  spring  and  generally  closes  in  November.  With  us  there 
is  no  closed  season  and  we  find  water  molds  wherever  the  water  is  open 
any  day  in  winter.  In  Denmark  Apodachlya  is  common,  while  Leptom- 
itus  is  not  recorded  by  Petersen.  In  Chapel  Hill  Leptomitus  is  very  com¬ 
mon,  while  Apodachlya  has  been  found  but  once. 

Our  experience  clearly  shows  that  vegetative  threads  and  gemmae 
are  in  all  species  killed  by  drying  up,  and  that  mature  eggs  may  resist 
drying.  This  is  also  the  conclusion  of  Petersen.  He  makes  the  inter¬ 
esting  statement  that  while  efforts  to  secure  cultures  from  dry  material 
in  many  cases  failed,  yet  growth  had  been  obtained  from  material  which 
had  been  in  a  dried  state  for  several  years.  As  regards  cold,  Petersen 
thinks  that  freezing  for  a  short  time  need  not  have  a  deadly  effect  on 
the  mycelium,  but  that  freezing  for  a  long  time  is  absolutely  destructive. 
We  find  that  in  all  but  one  of  the  species  {P ythio psis  cymosa )  we  have 
tested,  a  culture  allowed  to  freeze  solidly  over  night  is  all  killed  except 
the  eggs.  We  also  find,  with  Petersen,  that  darkness  has  no  bad  effect 
on  laboratory  cultures.  The  greater  abundance  of  individuals  or  species 


INTRODUCTION 


13 


in  open  sunny  marshes  and  ditches  is  probably  due  to  the  large  amount 
of  other  organic  life  in  such  places. 

As  to  parasitism,  of  which  much  remains  unknown,  Petersen  finds 
that  fish  are  little  attacked  in  natural  conditions  in  Denmark  and  then  only 
as  a  result  of  previous  injury.  He  seems  to  think  that  frog  eggs  may  be 
attacked  in  the  living  condition.  We  have  often  seen  eggs  of  frogs  and 
salamanders  overgrown  with  water  molds,  but  we  have  no  proof  that 
these  plants  were  the  actual  cause  of  the  death  of  the  eggs.  Petersen 
also  announces  that  Leptolegnia  caudata  is  the  fungus  which  attacks 
and  kills  great  numbers  of  the  crustacean  Leptodora  in  his  country. 
We  have  not  found  it  a  parasite  here. 

In  order  to  throw  light  if  possible  on  the  seasonal  distribution  of 
the  different  species  we  have  made  up  the  table  that  follows  this  page. 

Between  February  15,  1912,  and  December  15,  1913,  the  number 
of  collections  made  from  all  sources  around  and  in  Chapel  Hill  was 
593.  A  record  of  the  species  found  in  each  collection  was  kept  and  from 
these  records  and  the  number  and  date  of  the  collections  the  table  was 
drawn  up.  It  shows  the  per  cent  of  all  collections  in  which  each  species 
occurred  for  each  month,  for  spring,  summer,  fall  and  winter;  for  the 
six  warmest  months  (April-September  inclusive)  and  the  six  coolest 
months,  and  finally  the  per  cent  of  the  whole  number  of  collections  in 
which  the  species  was  found  compared  to  the  total  number  of  collections 
made  in  the  entire  period.  For  example,  Adilya  apiculata  was  found  89 
times  in  593  collections  or  in  15%  of  all  collections.  It  was  found  33  times 
in  138  collections  made  in  March,  or  in  23.9%  of  the  March  collections. 
The  number  of  collections  made  in  each  month  varied  considerably,  for 
example,  24  collections  were  made  in  July  and  138  in  March.  While 
this  does  not  interfere  with  accuracy  of  the  percentages,  it  does  give 
opportunity  for  a  larger  variation  of  percentages  in  months  with  fewest 
collections,  because  of  the  various  accidental  factors  involved  in  collecting. 
That  is,  the  larger  the  number  of  collections  the  less  the  percentage  of 
error  in  the  figure  showing  the  occurrence  of  a  certain  species  at  a  certain 
place  for  a  certain  time.  As  would  be  expected,  the  number  of  collections 
in  warm  months  was  less  than  in  the  cool  months,  due  to  the  absence 
of  members  of  the  staff  on  holidays.  There  were  237  collections  made  in 
the  six  warm  months  and  356  in  the  six  cool  months.  Since  19 1 3  we 
have  continued  steadily  at  work  on  this  group,  but  have  kept  no  exact 
data  as  to  the  number  of  collections, which  will  easily  run  into  several 
thousands. 

It  will  be  noted  that  Adilya  flagellata  and  A.  proliferoides  have  been 
run  together  in  the  table.  This  is  due  to  the  fact  that  the  two  species 
were  not  distinguished  for  some  time  after  the  records  began  and  went  in 


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INTRODUCTION 


15 


as  one.  Their  records  were,  therefore,  continued  as  one.  In  Aphanomyces 
the  species  occurring  in  Chapel  Hill,  except  A.  parasiticftfhzve  all  been 
combined,  as  the  genus  may  be  quickly  determined  by  the  sporangia, 
while  the  species  in  two  cases  are  often  to  be  settled  only  after  a  series  of 
cultures  to  secure  the  reluctant  production  of  oogonia. 

A  table  like  this  can  be  only  suggestive  and  proves  nothing  rigidly 
except  the  relative  abundance  of  the  species  at  different  seasons  in  any 
one  place.  This  may  be  shown  by  taking  the  case  of  Leptomitus.  It 
would  seem  from  this  table  to  be  a  rare  species  in  Chapel  Hill,  whereas 
it  may  be  had  any  day  by  collecting  in  streams  containing  sewage.  This 
point  makes  a  word  necessary  as  to  where  the  collections  were  made. 
In  order  to  make  the  record  mean  as  much  as  possible,  the  collections 
were  regularly  made  in  a  series  of  stations  of  considerable  variety  and 
the  great  majority  of  collections  were  made  in  the  same  series  of  stations. 
The  usual  series  were  several  collections  in  the  Arboretum  spring  and 
branch,  continuing  into  Battle’s  branch;  several  in  Terra  Cotta  spring 
and  the  pool  below  on  Glen  Burnie  farm;  several  in  the  seepy  marsh  at 
the  foot  of  Lone  Pine  hill  on  the  same  farm,  one  collection  occasionally 
in  Lone  Pine  spring,  and  several  collections  in  the  sedgy  marsh  in  front 
of  the  cemetery.  Not  rarely  collections  were  made  in  Howell’s  spring 
and  branch  and  its  branches,  and  scattering  collections  were  made  on 
occasion  in  many  other  places,  as  Bowlin’s  Creek  and  Morgan’s  Creek, 
New  Hope  Creek,  various  springs,  marshes,  troughs,  etc. 

When  we  analyze  the  table  we  see  that  for  the  great  majority  of 
species  spring  is  the  most  favorable  season  for  growth.  There  are  eleven 
species  which  were  found  in  a  greater  per  cent  of  the  collections  in  spring, 
three  in  winter,  three  in  summer  and  two  in  fall.  But  if  we  compare 
the  six  cold  and  the  six  warm  months  we  find  little  or  no  difference,  ten 
appearing  more  frequently  in  the  warm  and  nine  in  the  cold  months. 

The  present  volume  is  concerned  primarily  with  the  Saprolegniaceae, 
but  we  have  noted  the  genera  and  species  of  the  other  families  of  the  order 
Saprolegniales  and  have  treated  in  some  detail  all  species  in  this  order 
that  we  have  found  in  North  Carolina.  All  are  small  saprophytic  or 
parasitic  fungi  with  an  obvious  mycelium  growing  in  water.  We  have 
also  added  such  fungus  parasites  of  the  water  molds  as  have  appeared  in 
our  collections.  In  regard  to  the  culture  media,  when  the  word  ant  is 
used  it  refers  to  the  adult  worker  of  the  small  white  termite  that  is  com¬ 
mon  in  old  logs  and  stumps.  The  “spring  water  ’  mentioned  in  many 
notes  was  taken  from  the  spring  in  the  Arboretum  of  the  I  niversity. 

All  the  drawings  have  been  made  by  camera  lucida  and  nearly  all 
from  living  material.  The  author  is  responsible  for  the  photographs  and 


16 


THE  SAPROLFGXIACEAE 


for  the  majority  of  the  drawings,  but  many  of  the  more  recent  ones  have 
been  made  by  Mr.  Couch.  Plates  24  and  59  were  prepared  by  Air.  F.  A. 
Grant,  former  Assistant  in  Botany.  Miss  Alma  Holland,  Assistant  in 
Botany,  has  inked  in  nearly  all  of  the  plates. 

Key  to  the  Families  of  the  Saprolegniales 

Threads  of  the  plant  (mycelium)  not  constricted  into  joints  at  intervals;  oogonia  containing 
one  or,  more  often,  several  to  numerous  eggs  in  the  formation  of  which  all  the  protoplasm 
of  the  oogonium  is  used;  eggs  always  smooth,  not  completely  filling  the  oogonium 
except  in  Leptolegnia;  antheridia  present  in  most  species,  but  even  when  present 
fertilization  is  not  always  effected;  asexual  spores  biciliate,  diplanetic  or  monoplanetic 

Earn.  Saprolegniaceae  (p.  17) 

Plant  often  with  a  distinct  stalk,  the  threads  constricted  at  intervals  into  joints,  which  in 
the  vegetative  region  are  usually  connected  by  small  channels  through  the  nodes; 
oogonia  and  antheridia  present  in  most  species,  the  egg  always  single  and  with  periplasm, 
often  with  a  sculptured  surface;  spores  monoplanetic. ... Fam.  Leptomitaceae  (p.  169) 
Plant  with  a  distinct  enlarged  stalk  or,  if  the  base  is  not  distinctly  differentiated,  then  branched 
in  a  dichotomous  or  verticillate  way;  peculiar  resting  cells  present  which  are  probably 
parthenogenetic  eggs.  These  have  thick,  brown,  distinctly  pitted  walls  and  completely 
or  almost  completely  fill  the  thin-walled  oogonium,  out  of  which  they  often  slip  at  matur¬ 
ity.  Antheridia  absent.  Spores  with  one  (or  two?)  cilia,  monoplanetic.  In  one  genus 
( Allomyces )  the  plant  body  is  divided  into  cells  by  cross  walls,  a  condition  unknown 

in  any  other  member  of  the  order . Fam.  Blastocladiaceae  (p.  180) 

Plant  slender,  branched,  without  a  distinct  stalk;  not  constricted  into  joints;  egg  single, 
usually  sculptured,  in  some  species  ripening  outside  the  oogonium,  fertilized  by  an  active 
sperm  with  one  cilium.  Spores  uniciliate,  monoplanetic.  The  family  is  by  some  authors 
placed  in  an  order  of  its  own.  It  is  distinguished  from  all  other  fungi  by  the  retention 
of  an  active  sperm . Fam.  Monoblepharidaceae  p.  178) 


SAPROLEGNI ACEAE 


Key  to  the  Genera 

i.  Sporangia  rare  or  absent;  oogonia  with  very  thick  pitted  walls,  the  antheridia  arising 
from  immediately  below  them  and  running  up  their  sides . Aplanes{ p.  76) 


1.  Not  as  above . 2 

2.  Spores  normally  leaving  the  sporangium  by  a  common  mouth . 3 

2.  Spores  not  leaving  the  sporangium  by  a  common  mouth  (see  also  Adilya  ditbia) . 8 

3.  Spores  all  (normally)  swarming  separately  on  escaping  from  the  sporangium . 4 


3.  Spores  all  collecting  in  a  hollow  sphere  or  an  irregular  group  at  the  mouth  of  the  spor¬ 
angium  on  escaping . 7 

3.  Part  of  the  spores  on  emerging  swimming  away  or  sluggishly  jerking  away  and  encysting 

separately  from  the  remainder,  which  stop  at  the  sporangium  mouth.  Sporangia 
rounded  at  the  tip  and  not  tapering,  in  great  part  proliferating  cymosely  as  in  Adilya, 
but  at  times  threads  may  grow  through  empty  sporangia  as  in  Saprolegnia.  Eggs 
centric . Protoadilya  (p.  90) 

4.  Sporangia  not  thicker  than  the  vegetative  hyphae;  zoospores  in  a  single  row 

Leptolegnia  (p.  157) 

4.  Sporangia  usually  thicker  than  the  hyphae;  zoospores  not  in  a  single  row . 5 


5.  New  sporangia  formed  within  the  empty  ones . Saprolegnia  (p.  22) 

5.  New  sporangia  formed  in  greater  part  by  cymose  branching . 6 

6.  Antheridia  on  every  oogonium,  androgynous . Pythiopsis  (p.  17) 

6.  Antheridia  absent,  or  on  less  than  half  the  oogonia,  diclinous . Isoadilya  (p.  81) 


7.  Sporangia  usually  thicker  than  the  vegetative  hyphae;  zoospores  not  in  a  single  row 

Adilya  (p.  95) 

7.  Sporangia  not  thicker  than  the  vegetative  hyphae;  zoospores  in  a  single  row 

Aphanomyces  (p.  160) 

8.  Spores  encysting  within  the  sporangium,  then  emerging  separately  through  the  spor¬ 


angium  wall  and  swarming . Dictyuchus  (p.  150) 

8.  Spores  set  free  by  the  breaking  up  of  the  sporangial  wall . ThraustotJieca  (p.  148) 


PYTHIOPSIS  de  Bary,  1888,  p.  609. 

Hyphae  slender,  much  or  little  branched.  Sporangia  typically 
short  and  plump,  spherical,  oval,  pyriform  with  a  distinct  apical  papilla, 
or  varying  to  elongated  and  irregular,  primarily  borne  at  the  tips  of  the 
hyphae  and  multiplied  from  lateral  stalks  below  the  old  ones  to  form 
more  or  less  dense  clusters.  Spores  emerging  and  swimming  as  in  Sapro¬ 
legnia,  pip-shaped  with  two  apical  cilia,  sprouting  after  the  first  encyst- 
ment  (monoplanetic).  Gemmae  resembling  the  sporangia  or  oogonia, 
formed  plentifully,  often  in  chains,  producing  zoospores  after  a  rest. 
Oogonia  borne  like  the  sporangia  and  gemmae  and  resembling  them 
in  youth,  typically  spherical,  oval  or  pyriform  with  unpitted  walls. 


17 


1 8 


THE  SAPROLEGXIACEAE 


smooth  or  with  a  few  blunt  papillae.  Antheridia  short  and  thick,  typi¬ 
cally  androgynous  from  the  close  neighborhood  of  the  oogonia.  Eggs 
one  or  few,  eccentric,  with  a  lunate  cap  of  droplets  on  one  side  in 
P.  cymosa;  structure  doubtful  in  P.  Humphrey  ana. 

Key  to  the  Species 

Sporangia  globular  or  clavate;  oogonia  sometimes  with  a  few  blunt  outgrowths;  egg  single, 

14.8-18. 5m  thick .  P.  cymosa  (1) 

Sporangia  occasionally  elongated ;  oogonia  always  smooth ;  eggs  generally  one,  occasionally 

2,  and  very  rarely  4,  about  30m  thick . P.  Humphreyana  (2) 

i.  Pythiopsis  cymosa  deBary.  Bot.  Zeit.  46 :  631,  pi.  9,  fig.  1.  1888. 

Plate  I 

Hyphae  slender,  14.8-22.54  in  diameter  at  base,  short  or  moder¬ 
ately  long.  Sporangia  globular  or  clavate.  Spores  8.6-10.84,  most 
about  9(0.;  monoplanetic.  Oogonia  plentifully  formed  in  old  cultures, 
spherical  to  oblong  or  pear-shaped,  unpitted,  smooth,  or  sometimes 
with  a  few  blunt  outgrowths,  terminal  or  rarely  intercalary,  18-304 
in  diameter,  a  few  smaller.  Eggs  mostly  14.8-1 8.54  in  diameter,  but 
sometimes  up  to  244,  single  (Humphrey  says  rarely  two  to  an  oogonium) , 
eccentric,  as  described  above.  Antheridial  branches  short  or  none,  usually 
arising  from  just  below  the  basal  walls  of  the  oogonia,  rarely  diclinous. 
Antheridia  one  or  two  to  each  oogonium,  clavate;  antheridial  tubes  pres¬ 
ent,  at  times  growing  up  through  the  basal  wall  of  the  oogonium. 
Gemmae  of  more  or  less  globular  or  ovoid  shape  are  formed  in  quantity 
and  are  often  arranged  in  chains.  After  a  rest  these  also  form  zoospores. 

Rather  rare  in  springs  and  branches,  as  Terra  Cotta  spring,  branch 
in  Pritchard’s  pasture,  Glen  Burnie  meadow,  etc.  Collected  seven  times, 
and  all  in  winter.  Heretofore  reported  from  America  only  by  Humphrey, 
from  Amherst,  Mass.  See  his  plate  17,  figs.  60-68;  also  Alinden  (’12), 
figs.  3a,  3b  on  p.  556. 

The  species  may  be  easily  distinguished  from  P.  Humphreyana 
by  smaller  oogonia  with  sometimes  a  few  blunt  outgrowths,  smaller 
eggs,  smaller  sporangia,  presence  of  basal  antheridia,  and  absence  of 
elongated  forms  of  sporangia.  See  Mycologia  6:  285,  pi.  147,  1914, 
from  which  the  figures  and  most  of  the  following  notes  are  taken : 

The  sporangia,  oogonia  and  antheridia  are  well  shown  by  deBary 
and  Humphrey,  but  variations  occur  that  were  not  observed  by  them. 
The  antheridial  cells,  as  formed  in  about  one-half  the  oogonia,  are  unique 
in  position.  They  arise  by  the  enlargement  of  the  hypha  immediately 
below  the  oogonium  and  the  growth  of  this  segment  along  the  base  of 
the  oogonium  for  a  short  distance.  A  tube  is  formed  near  the  septum 
and  enters  to  the  egg.  As  the  antheridial  cell  is  in  close  contact  with 
the  oogonial  wall  from  the  septum  out,  the  position  of  the  septum  be- 


PLATE  1 


PLATE  1 

(From  Mycologia  6:  PI.  147.  1914) 

Pythiopsis  cymosa 

Fig.  1.  Oogonium  with  a  typical  sub-basal  antheridium.  X  720. 

Fig.  2.  Ditto,  with  an  additional  lateral  antheridium.  X  720. 

Fig.  3.  Ditto,  with  two  sub-basal  antheridia.  X  720. 

Figs.  4,  5,  6  and  7.  Oogonia  of  various  forms  with  antheridia  of  various  origin.  X  720. 
Fig.  8.  An  abnormal  double  oogonium,  apparently  without  an  antheridium.  X  720. 

Fig.  9.  Sporangia  of  typical  shapes.  X  447. 

Fig.  10.  Sporangia  about  one  minute  before  discharge  showing  the  spores  in  the  compress¬ 
ion  stage.  X  447. 

Fig.  II.  Gemmae;  one  having  discharged  spores  by  a  basal  papilla.  X  447. 

Fig.  12.  Spores,  killed  while  swimming:  one  with  four  cilia  and  double  size.  X  720. 


PLATE  1 


PYTHIOPSIS  CYMOSA. 


PYTHIOPSIS 


19 


comes  obscured  and  the  oogonium  seems  to  be  seated  at  maturity  on  a 
large,  swollen,  basal  cell.  Under  high  power,  however,  the  original 
septum  may  be  seen  as  a  somewhat  thicker  disc.  This  form  of  anther- 
idium,  as  shown  in  fig.  1  and  in  one  of  the  two  in  fig.  2,  is  not  exactly 
illustrated  in  either  deBary’s  or  Humphrey’s  figures.  From  this  strictly 
basal  and  closely  pressed  antheridium  we  have  in  the  remaining  half 
of  the  oogonia  all  sorts  of  variations.  The  antheridium  may  be  ele¬ 
vated  on  a  stalk  that  varies  from  nothing  to  half  the  length  of  the  oogo¬ 
nium  and  in  very  rare  cases  the  antheridium  may  be  even  of  diclinous 
origin  (figs.  5  and  6).  The  appearance  of  several  antheridia  on  one 
oogonium  is  of  rather  frequent  occurrence  in  our  cultures.  This  is  not 
recorded  by  deBary  or  Humphrey.  From  figures  3  to  7  an  idea  may 
be  gained  of  the  variations  observable  in  both  antheridia  and  oogonia. 
DeBary  does  not  give  the  size  of  the  eggs.  We  find  them  to  vary  from 
14.8  to  24(jl,  with  an  average  of  about  19.5^..  This  is  a  little  larger  than 
the  figures  given  by  Humphrey. 

The  remarkable  intercalary  oogonium  shown  in  fig.  8  is  unique. 
Its  single  egg  was  27.8  by  50^.  in  size  and  a  large  number  of  oil  drops 
were  grouped  at  each  end.  An  antheridial  cell  was  also  cut  off  at  each 
end,  but  no  antheridium  could  be  made  out. 

The  peculiar  jelly-like  outer  layer  that  deBary  noticed  on  the  oogonia 
in  October  cultures  was  also  seen  by  Humphrey  in  a  few  cases.  By 
careful  observation  we  have  been  able  to  make  out  this  layer  in  the  ma¬ 
jority  of  young  oogonia.  It  is  probably  present  on  all  at  a  certain  stage, 
but  in  clean  cultures  free  from  bacteria  is  very  hard  to  trace.  Its  pres¬ 
ence  and  outline  is  hardly  discernible,  except  for  the  bacteria  and  other 
minute  particles  that  stick  to  it.  As  remarked  by  Humphrey,  it  is  hardly 
possible  that  this  hyaline  gelatinous  outer  sheath  can  be  a  “periplasm” 
secreted  from  the  oogonium  contents,  as  deBary  suggests.  It  is  more 
apt  to  be  due  to  the  gelatinization  of  a  thin  outer  layer  of  the  wall  of 
the  oogonium. 

In  a  typical  clean  culture  in  spring  water  on  a  mushroom  grub  the 
sporangia  varied  from  37  to  56^  in  diameter,  the  majority  being  from 
44  to  48^  broad. 

In  figures  9  and  10  are  shown  sporangia  of  usual  appearance.  When 
the  sporangia  proceed  at  once  to  the  formation  of  spores  the  discharge 
is  usually  at  the  tip  (fig.  9).  If  a  rest  occurs,  the  immergence  tube  is 
as  apt  to  appear  at  the  base,  as  shown  in  fig.  1 1 .  After  the  first  sudden 
release  of  pressure  the  spores  do  not  rush  out  as  in  Achlya  and  Sapro- 
legnia,  but  emerge  much  more  quietly  as  they  find  the  opening.  The 
last  ones  often  swim  around  a  long  time  in  the  sporangium  before  finding 
an  exit.  The  spores  are  pear-shaped,  with  two  cilia  at  the  small  end. 


20 


THE  SAPROLEGNIACEAE 


On  coming  to  rest  they  round  up.  In  fig.  12  are  shown  three  normal 
spores  and  an  anomalous  double  one  with  four  cilia.  This  is  not  a  case 
of  fusion  after  emergence,  but  of  imperfect  segmentation  of  the  proto¬ 
plasm.  (See  remarks  on  page  9). 

Cultures  on  various  media  gave  the  following  results: 

On  corn  meal  agar.  Formed  plentiful  gemmae,  mostly  in  groups,  but  no  oogonia. 

On  boiled  butter  bean,  on  white  of  egg,  and  on  termites.  Showed  strong  growth,  a  great 
many  gemmae,  and  after  some  time  numerous  oogonia. 

On  boiled  willow  twig.  Showed  moderate  growth  and  a  few  oogonia. 

A  culture  in  pea  agar  was  left  outside  on  the  night  of  January  14,  1917.  It  was  frozen 
solid,  but  was  not  killed. 

The  following  experiments  were  made  to  determine  the  best  method 
of  preserving  live  cultures: 

A  culture  on  a  grub  was  placed  in  distilled  water  in  the  spring  of  1917,  but  when  tested  the 
following  September  was  found  to  be  dead. 

A  culture  on  corn  meal  agar  was  placed  in  a  vial  March  18,  1913,  and  was  found  to  be  dead 
when  tested  December  1,  1913. 

2.  Pythiopsis  Humphreyana  Coker.*  Mycologia  6 :  292,  pi.  148.  1914. 

Plate  2 

Vegetative  growth  of  long,  slender,  sparingly  branched  hyphae  about 
ii-I4[x  thick  which  are  stoutest  in  the  neighborhood  of  the  reproductive 
bodies,  and  which  after  maturity  disorganize  rather  quickly.  Sporangia 
varying  in  shape  from  spherical,  oval  or  pyriform  to  elongated,  tapering 
and  irregular  forms,  discharging  by  a  short  or  rather  long  papilla  and  usu¬ 
ally  proliferating  from  below  in  a  cymose  manner;  spores  monoplanetic, 
pear-shaped  and  with  two  cilia,  about  8.9;jl  in  diameter  on  coming 
to  rest.  Oogonia  generally  borne  exactly  like  the  sporangia  and  not 
to  be  distinguished  from  these  when  young,  apical  and  often  in 
groups  by  cymose  branching,  usually  spherical  with  a  basal  neck, 
sometimes  pear-shaped  and  rarely  longer  and  more  irregular,  varying 
greatly  in  size,  diameter  from  33  to  89^,  averaging  about  43p.;  wall 
always  smooth  and  unpitted,  about  i.4;jl  thick.  Eggs  generally  one, 
occasionally  two  and  very  rarely  four,  centric,!  diameter  from  24  to 
40;jl,  averaging  about  30[jl,  the  wall  about  2\x  thick,  not  so  nearly  filling 
the  oogonium  as  in  P.  cymosa;  antheridia  short-clavate,  terminating 
a  stalk  that  usually  arises  from  immediately  below  the  oogonium,  but 
sometimes  of  more  distant  origin,  or  rarely  diclinous,  one,  two  or  occa¬ 
sionally  more  on  every  oogonium  and  generally  applied  to  its  top  or 
distal  half,  with  an  antheridial  tube  which  reaches  and  apparently  fer- 

*Most  of  the  data  given  herewith  is  taken  from  the  original  description,  and  all  the 
drawings  except  two  were  published  there  also. 

fThey  were  reported  as  centric  in  the  original  description,  but  we  are  not  now  sure  of 
this.  Slides  fail  to  show  this  character  clearly. 


PLATE  2 


PLATE  2 

(Figs.  3-16  taken  from  Mycologia  6:  PI.  148.  1914) 

Pythiopsis  Humphreyana 

Fig.  1.  A  cluster  of  oogonia  some  with  diclinous,  others  with  androgynous  antheridia. 

x  370. 

Fig.  2.  Oogonia  borne  racemosely  with  androgynous  antheridia.  X  370. 

Fig.  3.  Sporangia  of  the  globular  form.  X  335. 

Fig.  4.  Two  sporangia  with  an  oogonium  and  antheridium.  X  335- 

Figs.  5-10.  Sporangia  of  various  forms.  Nos.  3  and  4  X  185;  others  X  125. 

Fig.  11.  An  oogonium  with  two  eggs  and  two  antheridia,  one  of  which  is  diclinous.  X  335- 

Fig.  12.  A  young  oogonium  with  antheridium.  X  335- 

Fig.  13.  Two  sporangia  with  oogonia  in  close  proximity.  X  185. 

Fig.  14.  A  sporangium  surrounded  by  several  oogonia.  X  185. 

Fig.  15.  An  oogonium  with  a  diclinous  antheridium,  showing  plainly  the  antheridial  tube. 
X  335- 

Fig.  16.  An  abnormal  oogonium  with  four  eggs.  X  335. 


PLATE  2 


PYTHIOPSIS  HUMPHREYANA 


PYTHIOPSIS 


21 


tilizes  the  egg.  Gemmae  resembling  sporangia  or  oogonia  are  present 
in  quantity,  and  after  a  rest  form  spores  or  germinate  with  tubes. 

Rather  rare:  occurring  only  eight  times  in  our  numerous  collections, 
as  in  brook  behind  Dr.  Henderson’s  residence,  February  29,  1912;  on  south 
side  Glen  Burnie  meadow,  March  18,  1912;  in  brook  in  Battle’s  Park, 
March  25,  1912;  in  branch  south  of  campus,  May  13,  1912,  etc. 

The  species  is  sharply  separated  from  P.  cymosa  by  the  much  larger 
and  always  smooth  oogonia,  larger  eggs,  larger  sporangia,  absence  of 
strictly  basal  antheridia  and  presence  of  elongated  forms  of  sporangia. 
Illustrations  of  the  globular  type  of  sporangia,  which  are  the  first  to 
appear  in  clean  and  vigorous  cultures,  are  given  in  figures  3,  4,  and  6. 
They  are  of  the  same  appearance  as  those  of  P.  cymosa.  The  papilla 
is  usually  formed  at  the  tip  when  growth  is  active,  but  if  there  is  a  rest 
it  is  as  apt  to  be  formed  at  any  other  point  (figs.  4  and  6).  Intermediate 
and  elongated  forms  are  shown  in  figs.  5-10  and  13.  As  in  P.  cymosa 
the  internal  pressure  is  dissipated  before  the  last  spores  emerge  and  it 
is  often  many  minutes  before  all  find  the  exit.  As  shown  in  the  figures, 
the  papilla  may  be  quite  abrupt  or  may  gradually  taper  into  the  body 
of  the  sporangium. 

The  oogonia  are  often  closely  associated  with  the  sporangia  (figs.  13 
and  14),  but  the  more  common  arrangement  is  a  terminal  oogonium 
on  a  rather  short  lateral  branch,  as  shown  in  fig.  2,  with  a  single  stalked 
antheridium  arising  from  immediately  below  it.  The  antheridial  branch 
almost  invariably  carries  but  a  single  antheridium,  which  is  short,  thick 
and  densely  filled  with  protoplasm.  The  antheridial  tube  is  quite  con¬ 
spicuous  and  its  behavior  is  such  that  there  is  scarcely  any  doubt  that 
fertilization  takes  place.  The  protoplasm  of  the  antheridium  passes 
into  the  tube  and  soon  afterward  no  protoplasm  or  tube  can  be  seen, 
indicating  the  discharge  of  the  former  and  collapse  of  the  very  thin- 
walled  tube.  The  tubes  are  distinctly  shown  in  figs.  13-15. 

Oogonia  with  two  eggs  are  not  very  rare.  One  of  these  with  two 
antheridia  is  shown  in  fig.  11.  Oogonia  with  four  eggs  were  seen  twice. 
One  of  these,  of  anomalous  shape,  is  shown  in  fig.  16.  I  he  occurrence 
of  more  than  one  egg  in  the  oogonium  of  P.  cymosa  is  quite  rare.  Hum¬ 
phrey  saw  two  eggs  only  once  and  our  cultures  of  that  species  have  not 
produced  any  such  oogonia.  DeBary  says  that  as  many  as  three  eggs 
may  occur  in  P.  cymosa  but  their  appearance  is  evidently  of  great  rarity. 


'y  ■> 


THE  SAPROLEGXIACEAE 


SAPROLEGNIA  Nees  v.  Esenbeck,  1823,  p.  513. 

Saprophytic  on  animal  or  plant  remains,  or  parasitic  in  some  species 
on  aquatic  animals  as  fish,  frog  eggs,  etc.  Exposed  hyphae  branched 
or  more  or  less  simple,  straight  or  crooked,  usually  tapering  gradually 
outward,  more  or  less  pointed,  springing  from  an  intricately  branched, 
in  part  rhizoid-like  mycelium  within  the  substratum;  all  vegetative 
parts  colorless  in  transmitted  light,  white  in  reflected  light,  the  threads 
not  septate  or  constricted  until  the  approach  of  reproductive  stages. 
Sporangia  at  first  terminal  on  main  threads,  typically  long-clavate  and 
thicker  toward  the  distal  end,  or  at  times  slender-fusiform,  often  irregu¬ 
lar  and  polymorphic  in  older  cultures;  at  maturity  opening  typically 
by  an  apical  mouth,  the  spores  emerging  rapidly  one  by  one  through 
pressure  from  within;  typically  proliferating  within  the  older  ones  in 
a  “nested”  fashion,  but  often  also  as  in  Achlya  (see,  for  example,  p.  26). 
Spores  pip-shaped,  with  two  apical  cilia,  swimming  away  as  soon  as  dis¬ 
charged,  soon  coming  to  rest  and  encysting  in  spherical  form;  after  a  few 
hours  emerging  again  through  a  minute  opening  in  the  cyst  and  swimming 
again  more  actively  in  a  somewhat  kidney-shaped  form  with  two  lateral 
cilia,  finally  coming  to  rest  on  a  nutrient  substratum  (if  such  is  available) 
and  sending  into  it  a  slender  tube  which  grows  and  branches  into  the  ex¬ 
tensive  mycelium  within.  Resting  bodies,  called  gemmae  or  chlamydo- 
spores,  of  very  variable  shape  and  size  formed  in  greater  or  less  number; 
often  in  chains  like  beads;  after  resting  for  a  few  days  the  contents  pro¬ 
ducing  spores  of  the  usual  type  which  emerge  by  a  variously  formed  mouth. 
Oogonia  terminal  on  main  threads  or  on  long  or  short  lateral  branches, 
or  in  some  species  intercalary  singly  or  in  chains;  shape  spherical  or  oval 
or  pyriform  or  when  intercalary  sometimes  fusiform ;  wall  smooth  or  papillate, 
often  pitted.  Eggs  one  or  many  in  an  oogonium,  formed  of  all  its  contents, 
but  never  completely  filling  it,  smooth,  the  protoplasm  entirely  surrounded 
by  one  or  two  layers  of  fatty  food  material  (centric  or  subcentric) ;  under¬ 
going  a  resting  period  before  sprouting.  Antheridia  present  or  absent,  of 
various  origin  and  appearance,  usually  terminating  slender  antheridial 
branches  which  are  short  or  long,  simple  or  branched,  and  originating 
from  the  same  threads  on  which  the  oogonia  they  reach  are  borne  (androgy¬ 
nous),  or  from  other  threads  (diclinous);  antheridia  when  present  often 
forming  one  or  more  slender  tubes  which  enter  the  oogonia  through  thin 
places  and  reach  the  eggs.  Fertilization  has  been  shown  to  take  place 
in  .S.  didina  and  S.  mixta  by  Trow  and  in  S.  monoica  by  Claussen  (see  these 
species  for  details).  For  a  good  account  of  spore  development  in  S.  ferax 
see  Rothert  (1888). 


SAPROLEGNIA 


23 


Natural  Key  to  the  Species* 

Sub-genus  Eusaprolegnia:  Eggs  averaging  more  than  two  in  an  oogonium,  truly  centric, 
with  a  single  layer  of  oil  drops  completely  surrounding  the  protoplasm,  or  subcentric, 
with  two  rows  on  one  side  and  one  on  the  other;  oogonia  with  or  without  pits,  smooth 
or  (in  one  species)  with  a  few  warts  on  some  of  the  oogonia 

Diclina  Group:  Oogonia  not  in  chains  or  if  so  not  tending  to  separate  at  maturity;  their 
walls  not  thick  and  the  pits,  if  present,  not  very  conspicuous;  antheridia  present,  their 
supporting  branches  at  least  in  part  long  and  branched 

I.  Antheridia  present  on  about  a  third  of  the  oogonia,  diclin- 

ous . S.  crustosa  var.  Ill  (p.  70) 

1.  Antheridia  present  on  all  or  nearly  all  the  oogonia .  2 

2.  Zoospores  less  than  20m  thick .  3 

2.  Zoospores  more  than  20/x  thick .  6 

3.  Antheridia  all  or  mostly  diclinous .  4 

3.  Antheridia  all  or  mostly  androgynous .  5 

4.  Spores  not  of  two  kinds 

Oogonial  wall  with  few  pits;  eggs  12-22 n  thick . S.  crustosa  var.  I  (p.  69) 

Oogonial  wall  with  few  pits;  eggs  17-2 7^  thick . S.  crustosa  var.  II  (p.  69) 

Oogonial  walls  without  pits  (except  where  the  antheridia  touch);  eggs  20-26 n 

thick . S.  diclina  (1) 

As  above,  but  eggs  averaging  30^  thick . S.  Kauffmaniana  (2) 

Oogonial  wall  with  numerous  pits;  eggs  12-22. 5^  thick . S.  stagnalis  { p.  70) 

Oogonial  wall  with  less  numerous  pits;  most  of  the  eggs  25-27^  thick.  .S.  delica  (3) 

4.  Spores  of  two  kinds,  large  and  small . 5.  anisospora  (4) 

5.  Oogonial  stalks  bent  and  often  coiled;  oogonial  wall  unpitted  or  the  pits  few  and 

(  S.  spiralis  (p.  7i\ 

inconspicuous . i  _  .  ;  ) 

(  S.furcata  (p.  72^ 

6.  Oogonia  borne  inside  the  host . S.  curvata  (p.  72^ 

Ferax  Group:  Oogonia  not  in  chains,  or  if  so  not  separating  at  maturity;  their  walls 
thick  and  usually  with  conspicuous  pits;  antheridia  at  times  absent,  but  usually  present 
on  a  varying  number  of  the  oogonia;  their  supporting  branches  short,  but  not  arising 
from  immediately  below  the  oogonia.  In  S.  parasitica  which  probably  belongs  in  this 
group  the  oogonia  are  absent. 

Antheridia  not  on  all  the  oogonia  (rarely  over  50%),  at  times  absent;  androgynous 
and  diclinous 

Antheridia  usually  on  not  more  than  15%  of  the  oogonia,  often  very  few  or 
none;  oogonia  often  found  in  old  sporangia  and  then  cylindrical;  eggs  com¬ 
monly  about  26 n  thick . . . S.  ferax  (5) 

Antheridia  absent;  oogonia  never  or  rarely  cylindrical,  eggs  usually  21-24M 

thick . *5.  lapponica  (p.  73) 

(See  also  S.  esocina  (p.  41) 

Antheridia  usually  on  about  half  the  oogonia  which  are  never  cylindrical;  eggs 

usually  24-25 n  thick . S.  mixta  (6) 

As  above  but  eggs  usually  16-19/x  thick . S',  mixta  var.  Asplundii  (p.  74I 

Antheridia  on  about  75 %  of  the  oogonia . S.  floccosa  (p.  74) 

*  The  absence  of  oogonia  in  S.  parasitica  makes  its  position  doubtful.  For  an  artificial 
key  see  below.  American  species  are  followed  by  a  number,  others  by  page  reference. 


2  4 


THE  SAPROLEGNIACEAE 


Antheridia  on  all  or  nearly  all  the  oogonia;  androgynous  or  rarely  diclinous 

Oogonia  commonly  on  short,  lateral  branches,  spherical  with  a  neck,  eggs 

usually  five  or  more  in  an  oogonium,  i6-22m  thick . S.  monoica  (7) 

As  in  S.  monoica,  except  that  the  eggs  are  usually  less  than  five  in  an  oogonium 

and  mostly  25-27^  thick . 5.  monoica  var.  glomerata  (8) 

As  in  S.  monoica,  but  no  oogonia  produced  except  in  a  solution  of  lucin  and  levu- 

lose . S.  monoica  var.  vexans  (9) 

As  in  5.  monoica  except  that  the  oogonia  have  longer  stalks  and  few  or  no  pits, 
and  that  the  vegetative  threads  are  longer  and  more  slender 

S.  monoica  var.  montana  (p.  75) 
Oogonia  commonly  on  rather  short  lateral  branches  or  also  intercalary,  spheri¬ 
cal  to  barrel-shaped  or  even  thread-like  with  a  row  of  eggs;  eggs  25-27 n 
thick  in  larger  oogonia,  17-22^  thick  in  small  ones;  antheridial  branches 

at  times  containing  eggs . 5.  paradoxa  (p.  75) 

Eggs  large;  than  above,  most  about  30-33 n  thick,  not  often  single 

S.  lit  oral  is  (10) 

Eggs  still  larger,  most  about  38/u  thick,  very  often  single. . .  .S.  megasperma(n) 
Oogonia  absent;  parasitic  on  fish,  etc.  (position  doubtful). . .  .S.  parasitica  (12) 

Hypogyna  Group:  Oogonia  not  in  chains,  their  walls  with  conspicuous  pits.  An¬ 
theridia  on  all  or  nearly  all  the  oogonia,  androgynous,  normally  formed  from  a  cell 
cut  off  from  the  oogonial  stalk  immediately  beneath  the  oogonium.  .S.  hypogyna  (13) 

Torulosa  Group:  (Position  doubtful;  may  go  properly  in  Isoachlya );  oogonia  in  large  part 

\  S.  torulosa  (14) 

in  chains;  antheridia  absent  or  very  few . )  s.  rhaetica  (p.  67) 

I  S.  variahilis  (p.  67) 

Sub-genus  Pseudosaprolegnia:  Eggs  as  a  rule  only  one  or  two  in  an  oogonium,  subcen¬ 
tric,  i.  e.,  with  the  protoplasm  completely  surrounded  by  small  oil  drops  which  are 
in  a  double  layer  on  one  side  and  a  single  layer  on  the  other.  Oogonia  covered  with 


blunt  papillae. 

Asterophora  Group:  There  is  but  one  species  in  the  subgenus . 5.  asterophora  (15) 

Artificial  key  to  the  Species* 

1.  Oogonia  absent;  parasitic  on  fish . S.  parasitica  (12) 

1.  Oogonia  present .  2 


2.  Spores  very  large  (25^  thick);  oogonia  formed  within  the  substratum 

5.  curvata  (p.  72) 

2.  Not  as  above;  oogonium  covered  with  blunt  papillae;  eggs  only  1-3  in  an  oogonium 

5.  asterophora  (15) 

2.  Not  as  above;  eggs  9-30  in  an  oogonium;  25-27/x  thick;  antheridial  branches  at  times 
containing  eggs . S.  paradoxa  (p.  75) 

2.  Not  as  above  in  all  respects .  3 

3.  Oogonia  in  chains,  androgynous  antheridia  on  each  oogonium 

See  A  planes  androgynus  (p.  77) 

3.  Oogonia  in  chains,  easily  separating,  antheridia  absent 

See  Isoachlya  monilifera  (p.  88) 


*American  species  are  followed  by  a  number,  others  by  a  page  reference. 


SAPROLEGNIA 


25 


3.  Oogonia  often  in  chains  but  mostly  single;  not  tending  to  separate;  antheridia  present 

on  some  (usually  few)  of  the  oogonia,  diclinous . S ee  Isoachlya  toruloides  (p.  82) 

3.  Oogonia  mostly  in  chains;  not  separating;  antheridia  none  /  S.  torulosa  (14) 

or  very  few,  androgynous  or  diclinous  . )  S.  rhaetica  ( p.  67) 

)  S.  variabilis  (p.  67) 
\  see  also  Isoachlya  (p.  8 1 ) 

3.  Oogonia  not  normally  in  chains;  antheridia  present  on  all  or  nearly  all  the  oogonia  4 

3.  Oogonia  not  normally  in  chains;  antheridia  absent  or  present  on  only  a  part  (rarely 

as  many  as  75%)  of  the  oogonia,  mostly  androgynous .  10 

3.  Oogonia  not  in  chains;  antheridia  present  on  only  about  a  third  of  the  oogonia, 

diclinous  . 5  crustosa  var  III  (p.  70) 

4.  Antheridia  all  or  nearly  all  diclinous .  6 

4.  Antheridia  all  or  mostly  androgynous .  5 

5.  Oogonial  stalks  bent  and  often  coiled;  oogonial  wall  unpitted  or  the  pits  few  and  in¬ 

conspicuous  . (5.  spiralis  (p.  71) 

(  S.  furcata  (p.  72) 

5.  Oogonial  stalks  not  coiled  or  much  contorted,  oogonial  wall  usually  with  pits  which  are 

often  conspicuous .  n 

6.  Spores  of  two  kinds,  large  and  small . 5  anisospora  (4) 

6.  Spores  not  of  two  kinds . .  g 

7.  Antheridial  branches  present  and  not  rising  from  immediately  below  the  oogonia; 

antheridia  on  all  or  nearly  all  the  oogonia .  8 

7.  Antheridial  branches  normally  absent;  antheridia  cut  off  from  the  top  of  the  oogonial 
stalk  . S.  hypogyna  (13) 

7.  Antheridial  branches  at  times  absent;  if  present  arising  from  immediately  below  the 

oogonium  (antheridia  always  present) . see  A  planes  Treleaseanus  (p.  79) 

8.  First  oogonia  mostly  terminal  on  main  hyphae,  often  oval;  eggs  large,  mostly  30-33 // 

thick  . S.  litoralis  (10) 

8.  Oogonia  commonly  on  short,  lateral  branches;  eggs  very  large,  30—52//  thick 

S.  megasperma  ( 1 1 ) 

8.  Oogonia  commonly  on  short,  lateral  branches,  spherical  with  a  neck,  eggs  usually  live 

or  more  in  an  oogonium,  16-22//  thick . S.  monoica  (7) 

8.  As  in  S.  monoica ,  except  that  the  eggs  are  usually  less  than  five  in  an  oogonium  and 

mostly  25-27/1  thick . 5.  monoica  var.  glomerala  (8) 

8.  As  in  5.  monoica  but  no  oogonia  produced  except  in  a  solution  of  lucin  and  levulose 

S.  monoica  var.  vexans  (9) 

8.  As  in  S.  monoica  except  that  the  oogonia  have  longer  stalks  and  few  or  no  pits,  and  that 

the  vegetative  threads  are  longer  and  more  slender.  .  .S.  monoica  var.  montana  (p.  75) 

9.  Oogonial  wall  without  pits  (except  where  the  antheridia  touch) ;  eggs  20-26/1  thick 

5.  diclina  (1) 

9.  Oogonial  wall  without  pits  (except  where  the  antheridia  touch);  eggs  averaging  30^. 

thick  . S.  Kauffmaniana  (2) 

9.  Oogonial  wall  with  numerous  pits;  eggs  12-22.5//  thick . S.  stagnalis  (p.  70) 

9.  Oogonial  wall  with  less  numerous  pits;  eggs  mostly  25-27//  thick . 5.  dehca  (3) 

9.  Oogonial  wall  with  few  pits;  eggs  17-27//  thick . S.  crustosa  var.  II  (p.  69) 

9.  Oogonial  wall  with  few  pits;  eggs  12-22/t  thick . S.  crustosa  var.  I  (p.  69) 

10.  Antheridia  usually  on  not  more  than  15%  of  the  oogonia,  often  very  few  or  none; 
oogonia  often  found  in  old  sporangia  and  then  cylindrical;  eggs  mostly  about  26// 
thick  . S  ferax  (5) 


26 


THE  SAPROLEGNIACEAE 


io.  Antheridia  absent;  oogonia  never  or  rarely  cylindrical,  eggs  usually  21-24M  thick 

5.  lapponica  (p.  73) 
See  also  5.  esocina  (p.  41) 

10.  Antheridia  usually  on  about  half  the  oogonia  which  are  never  cylindrical;  eggs  mostly 

24-25^  thick  .  5.  mixta  (6) 

10.  As  above,  but  eggs  mostly  only  16-19/z  thick . mixta  var.  Asplundii  (p.  74) 

10.  Antheridia  on  about  75%  of  the  oogonia . S.  floccosa  (p.  74) 


I.  Saprolegnia  diclina  Humphrey.  Trans.  Am.  Phil.  Soc.  17:  109,  pi. 
17,  figs.  50-53*  1892  [1893J. 

Saprolegnia  dioica  deBary.  Bot.  Zeit.  46:  619,  pi.  10,  figs.  12  and  13. 
1888. 

Not  S.  dioica  Pringsheim  or  N.  dioica  Schroeter  (which  see  under 
S.  ferax  and  S.  mixta). 

Plates  3,  4  and  14. 

Main  hyphae  of  moderate  size  and  length,  little  branched.  Spor¬ 
angia  only  slightly  enlarged  and  broadest  near  the  end,  repeatedly 
proliferating  inwardly,  but  also  not  rarely  arising  laterally  from  beneath 
the  discharged  ones,  as  in  Achlya.  Spores  11-11.54  in  diameter.  Gem¬ 
mae  very  abundant  and  variable  in  shape,  long  and  pointed  or  stocky 
and  knotted,  the  longer  ones  rather  characteristic  for  this  species,  the  other 
forms  much  as  in  S',  delica,  etc.  By  single  spore  cultures  made  several  times 
the  species  has  proved  to  be  not  dioecious  (heterothallic)  although  highly 
diclinous,  the  mycelium  from  a  single  spore  producing  both  oogonia  and 
antheridia.  Oogonia  spherical  or  oval  or  pear-shaped,  usually  with  a  short 
neck,  mostly  terminating  the  main  branches,  but  not  rarely  intercalary, 
occasionally  two  or  three  to  five  in  a  chain,  rarely  on  short  lateral  branches 
or  cylindrical  in  empty  sporangia,  very  variable  in  size,  even  in  the  same 
cultures,  35-1004  in  diameter;  walls  rather  thin,  without  pits  except  where 
the  antheridia  touch.  Antheridial  branches  arising  diclinously  from  near 
or  distant  hyphae,  branching,  delicate,  slender,  and  soon  disappearing  after 
the  antheridia  have  been  cut  off.  Antheridia  on  every  oogonium,  numerous, 
often  completely  covering  the  oogonium,  usually  slender  and  not  much 
larger  than  the  branches,  occasionally  somewhat  swollen  and  tuberous, 
only  moderately  dense,  but  remaining  visible  for  a  long  time  after  the 
antheridial  branches  have  disappeared.  Antheridial  tubes  nearly  always 
invisible  (if  present).  In  only  two  cases  were  they  seen.  (But  see  below 
for  Trow’s  statement  as  to  fertilization.)  Eggs  20-264  in  diameter,  most 
about  23-244,  varying  little  in  size  in  any  one  oogonium,  one  to  twenty 
or  more  in  an  oogonium,  usually  six  to  twelve,  centric. 

Common  in  branches  and  small  streams,  such  as  Arboretum  brook, 
Battle’s  brook,  branch  back  of  athletic  field,  etc.  Collected  in  Chapel 
Hill  76  times  between  February  29,  1912,  and  December  16,  1913  (see 
table),  and  found  many  times  since. 


PLATE  3 


PLATE  3 

Saprolec.nia  diclina 

Fig.  I.  Small  sporangia.  X  167. 

Fig.  2.  Sporangium  with  long  papilla.  X  167. 

Fig.  3.  Nested  sporangia.  X  167. 

Fig.  4.  Sporangia,  one  of  which  contains  sprouting  spores.  X  167. 
Figs.  5  and  6.  Various  forms  of  sporangia.  X  167. 

Figs.  7  and  8.  Gemmae  that  have  become  sporangia.  X  167. 

Fig.  9.  Intercalary  oogonium  with  characteristic  antheridia.  X  447. 
Fig.  10.  Chain  of  oogonia.  X  447. 

Figs.  II  and  12.  Oogonia.  X  447. 

Fig.  13.  Oogonia  containing  large  number  of  eggs.  X  447. 


PLATE  3 


SAPROLEGNIA  DICLINA. 


PLATE  4 


SAPROLEGXIA  MOXOICA  VAR.  GLOMERATA  [ABOVE].  X  6. 
SAPROLEGXIA  DICLIXA  [BELOW].  X  ABOUT  4. 


SAPROLEGNIA 


27 


Distribution:  Chapel  Hill,  Massachusetts,  Pennsylvania,  Alabama, 
Louisiana.  Also  listed  without  notes  by  Kauffman  as  found  by  Pieters 
in  Michigan  (’15,  p.  195). 

For  points  of  difference  between  this  and  5.  a?iisospora,  which  is 
nearest,  see  that  species.  From  A.  delica  it  is  distinguished  by  the  far 
less  numerous  and  larger  oogonia,  smaller  and  more  numerous  eggs, 
diclinous  antheridia  only,  and  the  quickly  disappearing  antheridial 
branches;  and  from  5.  ferax  by  the  numerous  antheridia  and  the  slightly 
pitted  oogonia.  For  other  illustrations  see  Minden  (’12),  fig.  ie  on  p. 
520;  Tiesenhausen  (’12),  figs.  4  and  5. 

This  is  one  of  our  commonest  species,  but  is  often  difficult  to  deter¬ 
mine  with  certainty  because  of  the  infrequency  of  sexual  reproduction 
at  room  temperature.  While  the  oogonia  are  not  rare  under  ordinary 
conditions  they  are  not  nearly  so  abundantly  formed  as  in  other  species, 
and  sometimes  many  cultures  will  be  made  before  they  are  found.  How¬ 
ever,  sexual  reproduction  can  be  greatly  increased  by  lower  temperature, 
and  can  nearly  always  be  obtained  in  an  ice  box. 

Trow  states  (’95)  that  fertilization  always  occurs  in  this  species 
(as  S.  dioica  deB.)  and  in  practically  the  same  way  as  in  S.  mixta ,  which 
see  for  some  detail. 

To  find  if  the  plant  is  really  dioecious  cultures  were  made  from  a 
single  spore  from  No.  10  of  October  25,  1912,  and  from  this  the  following 
five  cultures  were  made: 

Two  cultures  on  ants  were  madeabout  January  26th.  Onewasputonthewindowsilloutside, 
the  other  kept  in  the  laboratory.  By  February  10th  the  one  outside  had  formed  23 
typical  oogonia  that  were  crowded  with  numerous  antheridia  of  the  usual  distant 
origin.  The  oogonia  were  formed  close  in  to  the  ant,  as  commonly,  and  the  antheridial 
branches  were  very  delicate,  but  in  the  unusual  cold  they  did  not  disappear  so  soon. 
All  the  23  oogonia  were  measured  and  they  were  found  to  average  62.98;;.  in  diameter. 
The  largest  was  86.954,  the  smallest  40.74.  The  largest  had  about  20  eggs,  the 
smallest  2  eggs.  The  eggs  in  this  culture  ran  very  regular,  about  244  in  diameter. 
After  staying  out  for  about  three  weeks  without  a  freeze  this  culture  was  frozen  for 
about  36  hours.  Taken  in  and  tried  it  was  found  to  be  totally  dead  (unless  vitality 
remained  in  the  eggs:  they  would  not  sprout  at  the  time).  The  numerous  gemmae 
were  all  collapsed  and  dead.  The  culture  inside  also  formed  oogonia  of  usual  character; 
a  few  were  cylindrical.  Antheridia  very  numerous  and  thickly  enveloping  the  oogonia. 
Antheridial  branches  very  ephemeral.  As  usual  the  oogonia  were  sparse,  only  about 
50  in  the  culture.  Some  were  very  small  and  with  only  one  egg,  others  quite  large. 
On  an  ant  in  watch  glass  with  water  from  Arboretum  spring.  Many  sporangia,  about  6 
oogonia;  no  gemmae. 

On  an  ant  in  watch  glass  with  rain  water.  Exactly  like  the  above  in  appearance  and  result, 
except  that  there  were  no  oogonia.  New  ant  put  in  and  again  only  sporangia. 

On  an  ant  in  watch  glass  with  distilled  water.  No  oogonia. 


28 


THE  SAPROLEGNIACEAE 


Other  cultures  from  No.  io  of  August  25,  1912. 

In  egg  yolk  broth  only,  in  test  tube.  Abundant  growth,  dense  at  surface,  delicate  below. 
Surface  mat  with  a  vast  number  of  good  sized  gemmae  of  all  shapes.  A  good  many 
oogonia  (several  hundred)  with  fine  healthy  eggs  of  usual  size.  Antheridia  only  one  or 
two  to  an  oogonium,  or  seemingly  absent  from  many.  (Scarcity  or  absence  of  antheridia 
made  these  very  favorable  oogonia  for  study.  The  wall  is  rather  thin,  and  no  pits 
are  to  be  seen.) 

On  corn  meal  agar.  Growth  very  strong  and  healthy.  Many  large  gemmae  of  usual 
varied  shapes.  Nothing  else. 

In  pea  broth.  Culture  first  made  in  test  tube.  After  a  month  or  more  a  transfer  was  made 
to  watch  glass  with  new  pea  broth  to  see  if  the  plant  was  alive.  It  was  and  grew  well. 
This  last  showed  a  great  many  rather  small  gemmae  and  no  sexual  reproduction  or 
sporangia. 

In  egg  yolk  broth  on  ant.  Infected  by  a  bit  of  corn  meal  agar  culture.  Rapid  and  exten¬ 
sive  growth  throughout  dish.  Many  gemmae  and  sporangia  and  a  good  many  scatter¬ 
ing  oogonia  of  normal  appearance  with  antheridia  on  each,  but  much  fewer  than  usual. 
Eggs  of  normal  size  and  number,  but  in  some  cases  not  maturing. 

In  y2  maltose  peptone  +  y2  egg  yolk  broth.  Extensive  growth  of  fine  hyphae.  No  re¬ 
production  of  any  sort. 

On  corn  meal  egg  yolk  agar.  Growth  luxuriant,  covering  dish.  Immense  number  of  gem¬ 
mae.  No  oogonia. 

On  ant  in  pea  broth  (50  peas  boiled  an  hour  or  more  in  500  c.c.  of  water)  in  sterile  bottle. 
It  grew  well  and  when  examined  a  month  later  showed  an  extensive  mass  of  vegetative 
strands  and  a  very  few  empty  sporangia. 

Cultures  from  No.  9  of  August  26,  1912. 

In  pea  broth  on  yolk  of  egg,  single  spore  culture.  Growth  strong  and  heavy.  Numerous 
sporangia  and  large  gemmae.  No  oogonia. 

On  corn  meal  agar,  single  spore  culture.  Growth  very  strong  and  healthy.  Many  large 
gemmae  of  usual  varied  shapes.  Nothing  else. 

On  yolk  of  egg  in  distilled  water.  Abundant  sporangia,  very  abundant  gemmae  and  a 
good  many  oogonia  with  many  antheridia  to  each. 

In  maltose  5%  +  peptone  .01%,  single  spore  culture.  Luxurious  growth  filling  dish. 
A  good  many  sporangia,  some  liberating  spores,  some  not — in  last  case  the  contained 
spores  often  sprouted  in  position.  A  few  small  gemmae  were  formed. 

In  y2  haemoglobin  .05%  -f-  y2  KN2PO4  .1  %  on  ant  (the  culture  was  first  grown  to 
a  good  size  in  pure  water,  where  many  sporangia  were  formed,  and  then  transferred  to 
above  solution).  The  sporangia  did  not  empty  and  many  gemmae  formed. 

The  following  cultures  were  all  made  from  a  pure  culture  on 
corn  meal  agar;  the  first  six  contained  a  .2%  solution  of  the  salt 
and  a  .05%  solution  of  haemoglobin  JT : 

In  KNO3  +  haemoglobin.  Delicate  growth  of  rather  limited  extent.  Many  cylindrical 
sporangia,  most  of  which  retained  the  spores  which  sprouted  by  hyphae  in  position. 
Some  of  the  sporangia  discharged  a  few  spores,  but  most  remained  behind.  In  such 
cases  the  remaing  spores  sent  sprouts  through  the  open  tip  as  well  as  through  the 
sides.  Gemmae  very  few  and  small.  No  sexual  reproduction. 

In  KHsPCfi  -f  haemoglobin.  Delicate  growth  of  rather  limited  extent.  A  good  number  of 
gemmae  of  usual  normal  shapes.  No  sporangia  and  no  sexual  reproduction. 


SAPROLEGNIA 


29 


In  NAH2O4  +  haemoglobin.  Practically  no  growth. 

In  Ca3(P04)2  +  haemoglobin.  No  growth. 

In  K2SO4  +  haemoglobin.  Delicate  limited  growth.  Many  normal  sporangia,  often 
proliferating,  a  good  many  retained  all  or  part  of  the  spores,  which  did  not  sprout  in 
position.  Gemmae  rather  few  and  simple.  No  sexual  reproduction. 

In  Ca(N03)2  +  haemoglobin.  Delicate,  limited  growth.  A  few  sporangia,  all  retaining 
the  spores — no  spores  sprouting.  A  few  scattered  gemmae.  No  sexual  reproduction. 
In  lactic  acid,  1  drop  to  50  c.c.  H20.  No  growth. 

In  tannic  acid,  1  drop  to  10  c.c.  H20.  No  growth. 

The  following  experiments  were  made  to  test  the  best  method  of 
preserving  live  cultures: 

Single  spore  culture  (No.  10  of  October  25,  1912)  was  put  in  vial  of  water  in  May,  1913,  by 
cutting  out  piece  of  corn  meal  agar  on  which  it  was  growing.  The  vial  was  closed 
with  a  plug  of  cotton  and  put  in  a  dark  place  over  summer.  In  December,  1913,  tests 
showed  the  culture  dead,  except  for  about  %  the  eggs,  and  they  could  not  be  made 
to  sprout. 

The  same  test  was  made  for  culture  No.  5  of  April  19,  1913,  and  also  a  similar  test  using  a 
termite  ant  instead  of  a  bit  of  agar.  The  first  was  found  to  be  dead  in  December,  the 
latter  alive. 

The  same  two  tests  were  made  for  culture  No.  2  of  May  15,  1913,  with  exactly  the  same 
results. 

Another  test  was  made  by  putting  a  vigorous  growth  (single  spore  culture  of  No.  10  of 
October  25,  1912)  in  an  aquarium  jar  with  algae  on  the  laboratory  table  on  March  7, 
1913.  No  growth  appeared  on  insects  dropped  in  the  jar  September  18,  1917. 

2.  Saprolegnia  Kauffmaniana  Pieters.*  Bot.  Gaz.  60:488,  pi.  21.  1915. 

We  have  not  found  this,  and  the  description  is  from  Pieters, 
omitting  references  to  figures.  The  species  is  very  near  our  S.  diclina, 
of  which  it  may  be  only  a  variety  with  larger  eggs.  For  comparison 
between  this  and  61.  anisospora  see  under  the  latter. 

“This  species  was  collected  from  algal  material  in  the  botanical 
laboratory  of  the  University  of  Michigan,  of  unknown  source,  but  pre¬ 
sumably  from  around  Ann  Arbor. 

“Vegetative  growth  like  that  of  S.  ferax,  with  firm  stiff  hyphae; 
sporangia  freely  produced  and  of  the  same  size  and  appearance  as  in 
S.  ferax;  gemmae  round,  oval,  or  irregular  in  shape,  mostly  single,  some¬ 
times  in  chains  and  freely  produced;  oogonia  very  large,  on  long  or  short 
stalks,  or  intercalary;  scattered;  oval-  or  club-shaped,  very  rarely  almost 
round,  the  usual  size  being  about  70-80 x  1 00-250^.  The  smallest 
oogonium  noted  was  30x70^;  oogonium  wall  thin  and  smooth,  without 
pits;  oospores  from  3  or  4  in  small  oogonia  to  very  many  in  large  ones, 
averaging  about  20-30  oospores  per  oogonium;  oospores  average  about 
30p.  in  diameter,  contents  granular  without  any  conspicuous  oil  drop; 
antheridia  nearly  always  present,  only  occasionally  absent  on  inter- 

*  Dr.  Pieters,  who  published  this  as  S.  Kaufmanmana ,  an  incorrect  spelling  of  Dr. 
Kauffman’s  name,  in  reply  to  a  letter,  consents  to  a  change  to  5.  Kauffmaniana. 


30 


THE  SAPROLEGNIACEAE 


calary  oogonia,  diclinous,  of  various  shapes  from  clavate  to  clasping 
or  irregular,  often  curving  part  way  round  the  oogonium,  and  borne 
on  slender  antheridial  branches;  usually  more  than  one  on  an  oogonium. 

“This  species  seems  to  differ  decidedly  from  all  others  described, 
especially  in  the  large,  thin-walled  oogonia  without  pits.  Rarely  two 
oogonia  were  observed  in  series.  This  species  may  be  related  to  5. 
cinisospora,  of  which  species  little  is  known,  though  no  evidence  of  two 
kinds  of  zoospores  was  found  in  the  present  species.  Besides  its  marked 
morphological  characters,  S.  Kauffmaniana  is  interesting  from  the  fact 
that  it  is  especially  sensitive  to  the  concentration  of  haemoglobin.  Oogo¬ 
nia  were  but  sparingly  produced  on  flies,  many  cultures  having  none, 
and  no  culture  having  more  than  a  few.  Tests  were  made  by  trans¬ 
ferring  vigorous  mycelium  to  haemoglobin  solution,  and  it  was  found 
that  only  where  the  haemoglobin  had  a  concentration  of  0.025  per  cent 
were  oogonia  formed.” 

3.  Saprolegnia  delica  n.  sp. 

Plates  5  and  6. 

Growth  delicate  and  lax,  but  uniform  and  symmetrical,  the  hyphae 
straight  and  simple  at  first,  then  much  branched.  Sporangia  long, 
nearly  cylindrical  or  later  irregular,  abundant  and  symmetrical  in  most 
young  cultures,  the  later  ones  often  irregularly  inflated  or  bent,  repeat¬ 
edly  proliferating  from  within,  and  not  rarely  laterally  from  below; 
spores  about  10.5-11.5^  in  diameter;  gemmae  plentiful  or  few  (not  nearly 
so  abundant  as  in  5.  diclina),  spherical  or  pyriform  to  fusiform  or  clavate, 
often  in  moniliform  chains;  oogonia  typically  spherical,  abundant  on 
most  media,  terminating  the  main  branches  and  also  racemosely  borne 
throughout  on  rather  long  or  rarely  short  lateral  branches  that  are  usually 
two  or  more  times  as  long  as  the  diameter  of  the  oogonia;  wall  smooth, 
colorless,  thin,  about  i.8;x  thick,  furnished  with  rather  few  pits  about 
3. 7-8.510.  in  diameter  which  are  not  nearly  so  conspicuous  as  in  S.  monoica, 
S.  mixta  or  S.  ferax;  diameter  of  oogonia  on  termites  about  40-63^, 
averaging  about  55^,  on  fly  42-7010,,  averaging  about  6O[0.;  eggs  mostly 
1-6,  often  8,  and  very  rarely  up  to  16  (in  abnormal  cases  when  large 
oogonia  are  filled  with  very  small  eggs  there  may  be  up  to  40),  centric, 
quite  dark  when  young  (in  transmitted  light),  lighter  at  full  maturity, 
averaging  about  25-2 7 to.,  with  extremes  of  14.8-3310.,  the  smallest  often  in 
oogonia  of  normal  size  and  not  rarely  mixed  with  the  larger.  Antheridial 
branches  abundant,  often  long  and  rambling,  the  larger  part  diclinous, 
rather  stout  and  persistent;  antheridia  present  and  usually  numerous 
on  nearly  all  or  all  oogonia  (95-100%),  each  oogonium  typically  furnished 
with  at  least  one  diclinous  antheridium,  and  at  times  with  androgy¬ 
nous  ones  also,  occasionally  absent  from  oogonia  that  terminate  long 
branches  and  are  therefore  removed  some  distance  from  the  main  mass; 
pear-shaped  or  irregularly  tuber-shaped,  well  filled  with  protoplasm; 
antheridial  tubes  present  and  not  inconspicuous. 

A  very  common  species,  appearing  in  marsh  at  foot  of  Lone  Pine 
hill,  edge  of  pond  on  Glen  Burnie  farm,  brook  behind  athletic  field, 


PLATE  5 


PLATE  5 


Saprolegnia  delica 

Fig.  i.  Habit  of  fruiting.  X  iSS. 

Fig.  2.  Oogonium  with  androgynous  and  diclinous  antheridia.  X  503. 
Fig.  3.  Oogonia  with  androgynous  and  diclinous  antheridia.  X  188. 
Fig.  4.  Oogonium  showing  fertilizing  tube.  X  503. 

Fig.  5.  Oogonium.  X  503. 

Fig.  6.  Oogonia  with  ripe  eggs.  X  503. 

Fig.  7.  Oogonium  with  curiously  developed  antheridia.  X  503. 


PLATE  5 


SAPROLEGNIA  DELICA 


PLATE  6 


PLATE  6 

SArROLEGNIA  DELICA 

Fig.  I.  Sporangia.  X  278. 

Fig.  2.  Gemmae,  the  one  in  the  center  having  metamorphosed  into  a  sporangium.  X  278. 
Fig.  3.  Gemmae.  X  188. 

Fig.  4.  Oogonium  with  androgynous  and  diclinous  antheridia.  X  278. 

Fig.  5.  Oogonia.  X  188. 

Fig.  6.  Oogonium  and  sporangia.  X  503. 

Fig.  7.  Oogonium.  X  503. 

Fig.  8.  Abnormal  condition,  showing  a  small  oogonium  formed  within  the  larger  aborted 
original  (in  maltose-peptone  solution).  X  503. 


PLATE  u 


mm, 


/  1  •  *■ 

6  J§ 

iiA  /T^  ** 

)  s' 

<>  /  r  f  1 

••/  /  >Ji^  \  ,/  1 

v.f  U;'*.  )  (  1 

\ 

’■->»  's/\ 

(.>  s 

/•aV  •'•  •  /| 

>  A/-  "?'7 

LJ?  / 

.  ■  ■;  — s/  y 

.■•  '■■•■■■'  ;’r:  -ATva^V^i  I 

SAPROLEGXIA  DELICA 


SAPROLEGNIA 


31 


etc.,  also  in  creek  three  miles  north  of  Durham,  N.  C.  Cultures  from  a 
single  spore  produce  typical  growth  with  oogonia  and  antheridia. 

It  is  strange  that  this  has  not  been  described  before,  but  there  seems 
no  doubt  that  it  is  new.  The  thin  oogonial  wall  with  few  rather  obscure 
pits,  together  with  the  preponderance  of  diclinous  antheridia,  would 
indicate  a  relationship  to  the  Diclina  group.  It  seems  nearest  S.  ani - 
sospora,  which  see  for  resemblances  and  differences.  From  S.  diclina 
it  is  distinguished  by  abundant  oogonia,  with  fewer  eggs  (on  average) 
and  pitted  walls,  at  least  a  few  of  which  have  androgynous  antheridia 
at  some  stage  of  the  culture;  by  the  larger  and  more  distinct  antheridial 
branches  which  last  longer;  by  the  more  definite  and  thicker  antheridia, 
which  are  not  so  intricately  wound  over  the  oogonia  (though  sometimes 
so  numerous  as  to  cover  it) ;  by  much  fewer  gemmae,  and  by  the  appear¬ 
ance  of  a  part  of  the  oogonia  on  lateral  branches. 

It  does  not  seem  possible  to  refer  this  to  S.  semidioica  Petersen,  as 
the  antheridia  in  that  species,  so  far  as  can  be  made  out  from  the  descrip¬ 
tion,  are  essentially  androgynous,  arising  from  beneath  oogonia  and 
passing  to  the  oogonia  above  as  well  as  to  others  near.  Moreover 
the  eggs  of  Petersen’s  plant  are  too  numerous  (6-15)  and  small  (22^). 
We  agree  with  Minden  in  referring  that  species  to  S.  monoica  (which  see). 

In  regard  to  the  origin  of  its  antheridial  branches  the  species  is 
peculiar  and  apparently  whimsical.  As  said  above,  the  majority  are 
always  diclinous  (in  the  media  studied)  and  in  most  vigorous  cultures 
on  insects  the  proportion  of  oogonia  with  diclinous  antheridia  only  is 
very  high,  usually  over  95 %  and  often  99%.  However,  as  such  cultures 
get  older  the  per  cent  of  such  oogonia  may  drop  to  around  80%  and 
on  a  bit  of  boiled  corn  grain  the  oogonia  with  androgynous  antheridia 
may  reach  25%  (oogonia  with  androgynous  antheridia  nearly  always 
have  diclinous  ones  also),  and  on  whole  egg  agar  in  distilled  water  nearly 
50%.  Most  androgynous  antheridia  are  found  away  from  the  periphery 
of  the  culture  where  racemosely  borne  oogonia  are  rather  plentiful,  but 
on  a  corn  grain  even  the  terminal  oogonia  on  main  hyphae  may  often 
have  androgynous  antheridia  arising  beneath  (with  diclinous  ones  also, 
as  a  rule).  The  diclinous  antheridia  very  often  arise  from  hyphae  which 
also  bear  oogonia,  as  shown  in  the  figures. 

There  is  a  decided  preponderance  of  apical  oogonia.  Where  spor¬ 
angia  are  not  formed  abundantly  nearly  all  the  oogonia  are  apical. 
In  the  contrary  case  many  are  borne  also  on  short  lateral  branches. 

The  first  four  cultures  below  were  made  from  a  single  spore  cul¬ 
ture  of  No.  9  of  November  25,  1912: 

On  bit  of  egg  yolk  in  equal  parts  maltose  5%  an(l  peptone  .oif  0.  Extensive  growth  and 
very  abundant  gemmae.  No  sporangia  or  sexual  reproduction. 


THE  SAPROLEGNIACEAE 


32 

In  maltose  +  peptone  alone.  Growth  good,  filling  dish.  No  sporangia  or  gemmae. 
Many  inflated  oogonia,  with  normal  antheridial  threads  of  diclinous  origin  wrapped 
about  them,  but  no  antheridia  cut  off;  a  good  many  of  the  oogonia  with  eggs  in  a 
spherical  or  elliptic  secondary  oogonium  inside  and  at  the  tip  of  an  inflated  and  now 
empty  primary  one,  many  without  eggs  (pi.  6,  fig.  8).  The  wall  of  the  inside  oogonium 
may  be  pitted  and  that  of  the  outside  bladder  also  if  it  is  thick  enough.  (This  experi¬ 
ment  repeated  twice  with  single  spore  culture  from  No.  2  of  January  6,  1913,  again 
twice  with  No.  4  of  January  15,  1913;  again  with  No.  6  of  January  15,  1913,  and 
again  with  No.  6  of  February  20,  1913 — in  all  cases  with  the  same  results). 

On  white  of  egg  in  distilled  water.  Growth  delicate  and  short,  but  dense  and  healthy. 
Very  few  if  any  sporangia.  Abundant  oogonia,  with  healthy  eggs,  averaging  very 
small.  About  with  only  one  egg.  Antheridia  on  every  oogonium.  Where  there 
is  only  one  egg  there  is  usually  only  one  antheridium,  otherwise  usually  two  or  several. 
Antheridial  branches  not  quickly  disappearing. 

On  corn  meal  egg  yolk  agar.  Luxuriant  growth,  filling  dish.  Immense  number  of  oogonia 
with  one  or  more  antheridia  on  each,  all  apparently  of  diclinous  origin.  The  oogonia 
were  nearly  all  in  a  layer  just  below  the  surface  of  the  agar;  a  few  were  borne  above 
the  surface. 

On  whole  egg  agar  in  distilled  water.  Oogonia  terminal  on  main  branches  (generally),  or 
on  long  lateral  branches  which  are  two  or  more  times  (rarely  only  as  long  as)  the  diam¬ 
eter  of  the  oogonium.  Antheridia  on  each  oogonium,  often  there  are  both  androgy¬ 
nous  and  diclinous  antheridia,  nearly  always  some  diclinous;  androgynous  also  in 
about  y2  cases.  The  number  of  androgynous  antheridia  varies  a  good  deal  in  different 
parts  of  the  culture;  they  seem  to  be  present  where  the  growth  is  thickest  (  No.  2  of 
January  6,  1913). 

In  equal  parts  of  maltose  and  peptone  and  egg  yolk  broth.  Growth  extensive  and  delicate. 
Many  oogonia,  nearly  all  inflated,  many  maturing  good  eggs,  many  not.  Antheridial 
threads  very  numerous,  and  apparently  all  diclinous.  Antheridia  not  cut  off,  except 
in  a  very  few  cases.  No  sporangia  or  gemmae.  When  eggs  are  formed  they  are  cut 
off  in  a  special  wall  in  the  tip  of  a  bladder,  just  as  in  maltose  +  peptone  alone  (single 
spore  culture  from  No.  2  of  January  6,  1913). 

In  corn  meal  egg  yolk  gelatin.  Grew  well  and  covered  the  dish,  but  after  a  few  days  liquified 
the  medium.  No  reproduction  of  any  kind  (  No.  4  of  January  15,  1913). 

On  whole  egg  agar  in  distilled  water.  Oogonia  usually  terminal  on  main  threads;  often 
lateral  on  long  threads,  i.  e.,  on  stalks  two  or  more  times  their  diameter.  Antheridia 
on  every  oogonium,  nearly  always  (only  two  exceptions  seen)  diclinous  where  the 
oogonium  terminates  a  main  branch.  In  a  great  majority  of  cases  (about  90%)  also 
diclinous  where  oogonia  are  on  lateral  branches.  Short  branches  and  bumps  almost 
entirely  absent  beneath  the  oogonia  (  No.  6  of  January  15,  1913). 

The  next  three  cultures  were  made  with  collection  No.  1  of  No¬ 
vember  1 2,  1917: 

On  corn  meal  agar.  Growth  fairly  vigorous,  covering  plate.  Sporangia,  containing  spores 
which  remained  in  sporangia,  not  sprouting,  fairly  abundant.  Many  oogonia  with 
eggs.  Antheridia  present  on  about  90%  of  oogonia,  mostly  diclinous,  but  a  fair 
number  of  androgynous  ones  also. 

On  corn  meal  agar  cut  from  agar  of  preceding  experiment  in  pure  water  without  grub.  Few 
small  sporangia  formed  and  emptied  on  and  around  the  edges  of  the  agar.  Good  many 
oogonia  with  eggs  and  androgynous  and  diclinous  antheridia.  Oogonia  initials  were 
present  when  agar  was  cut  and  put  in  water. 


SAPROLEGNIA 


33 


On  boiled  corn  grain.  Growth  vigorous,  somewhat  more  curled  and  branched  than  on 
grubs  and  flies.  Sporangia  produced  as  normally.  Many  oogonia  with  eggs;  mostly 
terminal  on  main  hyphae.  Fully  50%  of  oogonia  had  no  antheridia.  This  culture 
was  repeated  with  the  same  results  except  that  about  75%  of  oogonia  produced  were 
furnished  with  antheridia. 

The  following  experiments  were  to  test  the  best  method  of  preserv¬ 
ing  live  cultures: 

Single  spore  culture  from  No.  9  of  November  25,  1912,  put  in  aquarium  jar  with  algae  on 
March  3,  1913.  Was  found  to  be  dead  when  tested  for  life  on  September  18,  1917. 
Single  spore  culture  from  No.  2  of  January  6, 1913,  put  in  an  aquarium  jar  with  algae  on  the 
laboratory  table  on  March  7,  1913.  Was  found  to  be  dead  when  tested  for  life  on 
September  16,  1917. 

Single  spore  culture  of  No.  6  of  January  15,  1913,  put  in  an  aquarium  jar  with  algae  on  the 
laboratory  table  on  March  3,  1913.  Was  found  to  be  dead  when  tested  for  life  on 
September  16.  1917. 

Single  spore  culture  from  No.  9  of  January  25,  1912,  put  in  vial  on  corn  meal  agar  April 
10,  1913,  and  was  found  to  be  alive  December  1,  1913. 

Single  spore  culture  from  No.  4  of  January  15,  1913,  put  in  vial  on  ant  larvae  April  10.  1913, 
and  was  found  to  be  alive  December  1,  1913,  and  furnished  growth  from  gemmae. 
All  eggs  had  disorganized. 

4.  Saprolegnia  anisospora  deBary.  Bot.  Zeit.  46: 619,  pi.  9,  fig.  4.  1888. 

Plates  7,  8,  9,  and  10. 

Main  hyphae  about  5-8  mm.  long  on  a  mushroom  grub,  of  moderate 
size  at  base,  but  quickly  becoming  smaller,  the  culture  appearing  quite 
delicate  in  comparison  with  many  other  species;  main  hyphae  from 
404  in  diameter  below  to  114  or  even  less  near  the  tip.  Sporangia  usually 
borne  on  larger  branches  than  the  oogonia  (but  a  good  many  oogonia 
also  borne  on  the  larger  branches),  usually  rather  stocky  and  irregu¬ 
lar  and  largest  in  the  middle  or  near  the  base,  sometimes  regularly 
tapering  towards  the  end,  very  variable  in  size  in  the  same  culture, 
about  8.6-15.24,  rarely  up  to  16.64  thick,  usually  thicker  than  the  strand 
that  bears  them,  often  short  and  broad;  proliferating  as  usual  in  Sapro¬ 
legnia ,  or  when  in  distilled  water  the  greater  part  as  in  Achlya.  Dictio- 
sporangia  have  been  several  times  observed.  Spores  remarkable  in  being 
of  two  kinds,  large  and  small  and  often  intermediate  sizes,  usually  in 
separate  sporangia  without  constant  regard  to  the  size  of  the  latter,  a 
single  sporangium  usually  with  spores  of  only  one  size,  but  occasionally 
they  are  mixed;  the  smallest  spores  about  8-94  in  diameter,  others 
from  10. 5-1 1.54,  the  large  ones  from  13.7-14.84;  small  and  large  spores 
similar  in  structure,  but  the  small  are  greatly  in  excess  of  the  large 
ones;  in  nearly  all  cultures  there  are  formed  in  addition  a  few  very 
large  spores  at  least  twice  the  bulk  of  the  ordinary  large  spores,  these 
appearing  usually  mixed  with  the  latter. 

Oogonia  numerous  and  formed  in  all  ordinary  culture  media,  borne 
usually  on  the  tips  of  long  slender  branches  which  arise  from  near  the 
substratum,  often  intercalary  (very  rarely  two  or  three  in  a  row),  varying 
to  laterally  sessile  or  on  short  or  rather  long  lateral  branches;  typically 


34 


THE  SAPROLEGNIACEAE 


spherical  with  a  short  neck  when  apical,  but  at  times  oval  to  pear-shaped, 
and  when  intercalary  oblong  to  flask  or  spindle-shaped  with  long  necks; 
33-9 2[i  in  diameter,  most  about  55-65^;  at  maturity  with  moderately 
thick  walls  that  appear  unpitted  except  beneath  each  antheridium, 
where  there  is  always  a  distinct  circular  pit  (when  young,  just  before 
the  formation  of  the  egg  initials,  the  oogonia  present  a  spotted  appear¬ 
ance  from  the  arrangement  of  droplets  of  oil  in  the  protoplasm,  as  is 
usual  in  the  family).  Eggs  1-20,  mostly  4-6,  quite  variable  in  size 
even  in  the  same  oogonium,  17-38^  in  diameter  (not  rarely  some  very 
small  ones  as  little  as  13^  thick),  most  about  21-27^,  centric. 

Antheridial  branches  quite  slender  and  soon  becoming  very  in¬ 
conspicuous,  arising  from  any  of  the  main  branches,  usually  from  the 
proximal  half,  and  running  to  oogonia  on  other  branches  than  the  one 
from  which  they  arise  (diclinous);  oogonial  branches  often  give  rise 
to  antheridial  branches  lower  down.  Antheridia  cylindrical  or  tuber¬ 
ous,  present  on  all  oogonia,  usually  several  to  many,  when  young  well 
filled  with  protoplasm,  in  age  apparently  empty;  antheridial  tubes  formed 
in  most  cases  and  remaining  visible  for  some  time  after  the  eggs  are 
formed.  Gemmae  more  or  less  numerous  or  rather  few,  usually  spherical, 
sometimes  pear-shaped  or  tuberous  and  of  other  shapes,  usually  in  short 
or  long  chains,  easily  becoming  sporangia  on  change  of  conditions,  empty¬ 
ing  by  a  proliferating  tube.  Often  there  may  be  several  proliferation 
tubes,  but  only  one  opens  for  the  escape  of  the  spores. 

Rare,  and  found  only  three  times,  twice  in  Chapel  Hill  collections, 
from  Arboretum  branch  (No.  12  of  January  30,  1913),  and  from  a  marshy 
sink  opposite  the  cemetery  (No.  2  of  January  2,  1917),  and  once  in  Wil¬ 
mington,  N.  C.,  in  a  ditch  at  the  golf  links,  this  last  a  form  with  some¬ 
what  larger  oogonia  and  more  numerous  eggs.  No.  12  of  January  30, 
1913,  was  cultivated  for  about  four  months  from  a  single  spore  and 
No.  2  of  January  2,  1917,  was  cultivated  for  a  year  and  a  half,  part  of 
the  time  from  a  single  spore.  The  species  is  distinguished  by  its  char¬ 
acteristic  sporangia,  two  or  more  sizes  of  spores,  and  diclinous  anther¬ 
idia  on  every  oogonium. 

The  frequent  appearance  of  two  or  three  sizes  of  spores  recalls  N. 
anisospora,  and  we  have  become  convinced  that  our  plant  is  that  species. 
But  for  the  centric  eggs  there  is  no  great  difference  to  be  noted  in  de- 
Bary’s  description.*  In  fact,  the  small  oogonia  with  unpitted  walls, 
the  small  number  of  eggs,  the  numerous  and  conspicuous  diclinous  an¬ 
theridia  on  each  oogonium,  and  the  very  variable  spores  form  so  striking 
a  set  of  similar  characters,  particularly  as  in  this  group  of  characters 
both  species  are  well  separated  from  all  others,  that  one  is  inclined  to  sus¬ 
pect  that  deBary,  who  rarely  made  a  mistake,  was  in  this  case  wrong  in 

*DeBary’s  description  of  the  oogonia  as  club-pear-shaped  is  evidently  a  distinct  ex¬ 
aggeration  of  the  tendency  to  that  shape.  His  figures  show  oogonia  that  are  spherical  or 
slightly  pear-shaped. 


PLATE  7 


PLATE  7 

Saprolegnia  anisospora 

Fig.  I.  Spore  masses  which  came  out  of  sporangia  without  breaking  up. 
Fig.  2.  Gemmae.  X  1 88. 

Fig.  3.  Gemma  with  three  papillae.  X  188. 

Fig.  4.  Gemma  with  six  papillae.  X  188. 

Fig.  5.  Gemma  and  sporangia.  X  503 
Fig.  6.  Young  oogonium.  X  503. 

Fig.  7.  Resting  sporangia.  X  188. 

Fig.  8.  Young  oogonium.  X  503. 

Figs.  9,  10.  Oogonia  containing  many  eggs.  X  503. 


X  810. 


PLATE  7 


SAPROLEGNIA  AXISOSPORA 


PLATE  8 


PLATE  8 

Saprolegnia  anisospora 

Figs.  1-3.  Various  forms  of  sporangia.  X  188. 

Fig.  4.  Gemma  which  has  become  a  sporangium  with  small  spores. 
Figs.  5  and  6.  Forms  of  sporangia.  X  188. 

Fig.  7.  Large  spores  in  amoeboid  state.  X  Sio. 

Fig.  8.  Large  spore  encysted.  X  810. 

Fig.  9.  Large  spore  with  cilia.  X  810. 

Fig.  10.  Sporangium  in  act  of  emptying  large  spores.  X  188. 

Fig.  11.  Sporangium  containing  large  spores.  X  503. 

Fig.  12.  Sporangia.  X  188. 

Fig.  13.  Gemma  with  long  papilla,  emptying  spores.  X  503. 

Fig.  14.  Small  spore  encysted.  X  810. 

Fig.  15.  Small  spore  coming  out  of  cyst.  X  810. 

Fig.  16.  Three  small  spores  in  first  swimming  stage.  X  810. 


x  503- 


PLATE  S 


PLATE  9 


PLATE  9 

Saprolegxia  anisospora 

Fig.  i.  Proliferating  sporangia.  X  278. 

Fig.  2.  Intercalary  oogonium.  X  188. 

Fig.  3.  Young  oogonia  with  antheridia,  showing  habit.  X  188. 

Fig.  4.  Oogonium  with  two  ripe  normal  eggs  and  two  others  going  to  pieces.  X  503. 

Fig.  5.  Sessile  oogonium.  X  503. 

Fig.  6.  Oogonium  in  old  sporangium.  X  503. 

Fig.  7.  Oogonia  in  a  chain.  X  188. 

Fig.  8.  Chains  of  gemmae  with  oogonia  on  tip  in  two  cases;  the  oogonium  on  the  right  with 
all  its  contents  rounded  up  into  a  single  mass  which  formed  a  wall,  but  did 
not  take  on  the  typical  internal  structure  of  an  egg.  X  188. 

Fig.  9.  Intercalary  oogonium  with  eggs  of  varied  size.  X  278. 

Fig.  10.  Gemma  emptied  by  a  long  papilla.  X  278. 

Fig.  11.  Odd-shaped  oogonium  with  a  single  egg.  X  503. 

Fig.  12.  Intercalary  oogonium  containing  large  and  small  egg.  X  503. 

Fig.  13.  Cluster  of  Pythiopsis-Yike  sporangia.  X  188. 


PLATE  9 


SA  P  ROE  EG  X I A  AX  I SOSPO  R  A 


PLATE  10 


PLATE  10 

Saprolegnia  axisospora 
Fig.  I.  Habit  of  oogonia  and  antheridia.  X  188. 

Figs.  2,  3,  and  4.  Formation  of  eggs  and  growth  of  antheridial  tubes  in  the  same  oogonium. 

No.  4  was  drawn  15  minutes  later  than  No.  3.  X  536. 

Figs.  5  and  6.  Oogonia  attacked  by  a  parasite  that  seems  to  be  a  blue-green  alga.  X  503 
and  810. 


PLATE  10 


SAPROLEGNIA  ANISOSPORA.  FORM  B. 


SAPROLEGNIA 


35 


thinking  the  normal  eggs  eccentric.  His  figures  clearly  show  eccentric 
eggs,  but  may  they  not  have  been  breaking  down?  This  seems  the 
more  likely  as  no  other  Saprolegnia  has  an  eccentric  egg.  Moreover, 
deBary  found  his  plant  only  once  (in  a  small  swamp  at  Strassbourg) 
and  had  it  in  cultivation  only  two  months  before  losing  it.  He  grew 
cultures  from  a  single  large  spore  and  found  them  to  produce  both  large 
and  small  spores.  Our  pure  cultures  were  made  from  single  spores, 
but  whether  large  or  small  was  unfortunately  not  noted.  They  pro¬ 
duced  both  oogonia  and  antheridia,  as  described  above.  This  proves 
that  at  least  one  of  the  two  sorts  of  spores  is  bisexual.  Fischer  (’92,  p.  337) 
suggests  that  the  small  spores  may  be  male  (and,  by  implication,  the 
large  ones  female). 

Since  deBary’s  day  no  one  seems  to  have  found  the  plant  except 
Obel,  who  casually  refers  to  it  in  his  paper  on  oogonia  formation  in  Achlya 
decorata  (Ann.  Mycologici  8:  422.  1910),  saying  that  “Cultures  of  this 
species  grown  up  from  the  great  [larger]  zoospores  may  be  low  and  crowded 
with  oogonia,  while  cultures  grown  up  from  old  gemmae  may  be  large 
and  quite  free  from  oogonia  generation  after  generation.”  He  does 
not  further  enlighten  us  on  the  important  point  as  to  whether  the  cul¬ 
tures  from  gemmae  ever  do  form  oogonia. 

This  species  is  apparently  nearest  S.  didina ,  as  indicated  by  the 
strictly  diclinous  antheridia  on  every  oogonium,  the  unpitted  wall  of 
the  oogonia,  and  the  apical  or  intercalary  position  of  the  oogonia.  It 
differs  from  that  species  in  the  spores  of  two  or  more  sizes,  in  the  smaller, 
more  spherical  oogonia  (apical  oogonia  of  S.  didina  are  mostly  oval), 
with  fewer  eggs,  which  are  abundantly  borne  at  room  temperature,  in 
the  more  conspicuous  antheridial  branches  which  do  not  disappear  so 
quickly,  in  the  large  and  tuberous  antheridia,  and  in  the  absence  of  the 
abundant  long  gemmae  of  S.  didina.  Saprolegnia  Kauffmaniana  differs 
in  about  the  same  respects. 

In  the  appearance  of  the  culture,  the  abundance  and  size  of  the 
oogonia  and  in  number  of  eggs  the  species  is  like  S.  delica,  but  is  easily 
distinguished  from  it  by  the  unpitted  oogonial  walls,  the  many  inter¬ 
calary  oogonia,  and  by  constantly  diclinous  antheridia.  In  the  several 
collections  that  we  have  measured  the  oogonia  of  S.  anisospora  average 
about  j1  to  ^  larger  than  in  S.  delica  on  the  same  medium. 

A  rather  frequent  abnormality  is  that  shown  in  the  oogonium  on  pi.  9, 
fig.  8.  The  protoplasm,  instead  of  dividing  into  several  eggs,  rounds 
itself  up  into  a  single  dense  mass,  the  size  of  the  combined  eggs  of  a 
normal  oogonium,  the  mass  remaining  homogeneous,  as  in  a  gemma, 
but  denser,  and  not  taking  on  the  centric  structure  of  a  normal  egg. 
Such  masses  might  be  considered  as  modified  gemmae  rather  than  eggs. 


36 


THE  SAPROLEGXIACEAE 


In  the  Wilmington  plant,  that  we  will  call  Form  B,  the  oogonia  and 
the  number  of  eggs  run  distinctly  larger,  all  other  characters  the  same. 
For  example,  two  cultures  of  each  were  compared,  one  of  each  on  a  piece 
of  corn  grain,  and  one  of  each  on  a  mushroom  grub.  On  the  corn  the 
Chapel  Hill  plant  showed  oogonia  33-8  px;  eggs  1-8,  mostly  2-6,  many 
single;  while  Form  B  showed  oogonia  65-93^,  eggs  4-20,  mostly  8-12 
in  an  oogonium.  On  a  grub  the  former  showed  oogonia  40-64^,  eggs 
1-5,  mostly  2-4,  while  Form  B  showed  oogonia  48-70^,  eggs  2-8,  mostly 
4-6.  In  Form  B  the  first  cultures  which  were  made  in  the  ditch  water 
with  algae,  etc.,  in  which  it  was  taken,  showed  a  remarkable  abnor¬ 
mality  (pi  10,  figs.  5  and  6).  A  good  many  of  the  oogonia  were  much 
swollen  to  as  much  as  twice  the  average  size  (up  to  150^.),  while  the  eggs, 
which  were  no  greater  in  number  than  usual,  were  in  great  part  disorgan¬ 
ized,  often  only  one  or  two  maturing.  The  disorganized  eggs  would 
usually  reach  the  point  of  forming  a  thin  wall,  and  would  then  go  to 
pieces  inside.  This  condition  was  not  thoroughly  realized  until  after  the 
culture  had  been  purified  on  agar  and  the  abnormality  thus  arrested. 
It  was  then  found  from  slides  that  the  enlarged  oogonia  contained  a 
parasitic  organism  with  the  exact  appearance  of  a  blue-green  alga,  which 
ran  among  the  eggs.  There  was  not  the  least  resemblance  to  the  ordinary 
fungal  parasites  that  attack  the  water  molds,  and  it  is  to  be  regretted 
that  the  parasite  was  lost  before  it  could  be  more  thoroughly  studied. 
It  is  of  interest  to  note  the  close  resemblance  of  this  parasite  to  the  one 
shown  by  Reinsch  (’78)  in  his  fig.  11,  pi.  14.  He  considered  the  parasite 
a  species  of  Saprolegnia ,  but  gives  no  reason  for  thinking  so. 

The  following  observations  were  made  on  the  Wilmington  Form  B 
by  Mr.  J.  N.  Couch,  Instructor  in  Botany:  “The  oogonial  wall  is  thick¬ 
ened  just  before  the  protoplasm  draws  away  to  form  the  egg  initials 
and  as  the  eggs  become  rounded  the  fertilizing  tubes  appear.  They  grow 
rapidly  and  in  fifteen  minutes  have  reached  the  eggs.  Granules  were 
observed  to  pass  slowly  down  the  tubes  and  some  of  them  seemed  to  dis¬ 
appear  into  the  eggs.”  The  notes  given  below  all  refer  to  the  Chapel 
Hill  form. 

Repeated  cultures  in  spring  water  show  that  growth  through  old 
sporangia  is  much  more  common  in  spring  water  than  in  distilled  water, 
where  there  is  a  strong  tendency  to  proliferate  as  in  Adilya. 

On  emergence  the  large  spores  are  elongated  and  often  bent,  squar¬ 
ish  at  one  end.  They  change  this  shape  to  pear-shape  in  a  few  seconds. 
The  ciliated  end  usually,  if  not  always,  emerges  last.  The  opposite 
end  is  often  indented  on  emergence.  Both  large  and  small  spores  ap¬ 
peared  in  large  numbers  in  a  hanging  drop  of  sporangia  and  gemmae 
in  pure  water.  The  spores  are  certainly  diplanetic:  some  sporangia  were 


SAPR0LEGN1A 


"7 

6/ 

put  on  a  slide  in  water  in  a  moist  chamber  to  test  this  again.  Many  spores 
were  formed  and  coming  to  rest  on  the  slide  emerged  again,  leaving 
a  large  number  of  cysts. 

The  following  notes  were  made  on  the  development  of  the  spores: 
At  one  o’clock  the  outlines  could  be  seen.  These  would  appear  and 
then  almost  disappear  in  different  parts  of  the  sporangium.  This  happened 
several  times.  At  1:16  the  whole  sporangium  rapidly  became  homo¬ 
geneous.  After  about  4  minutes  the  spore  outlines  began  again  to  appear 
and  became  pretty  plain  in  five  minutes.  They  continued  in  this  con¬ 
dition,  the  outlines  getting  gradually  more  distinct,  for  about  15  minutes 
without  change.  All  this  time  the  spores  (or  protoplasm)  were  firmly 
touching  the  wall,  but  now,  about  4  minutes  before  emerging,  there 
could  be  seen  a  narrow  space  filled  with  sap  between  the  spores  and  the 
wall.  The  spores  emerged  at  1 142,  popping  out  rapidly  at  first  under 
strong  pressure  and  gradually  reducing  the  pace.  As  soon  as  the 
sporangium  opened  the  column  of  spores  shrank  from  the  wall  in 
proportion  as  the  escape  permitted,  the  last  ones  forming  a  narrow 
column  right  in  the  center.  On  emptying  the  sporangium  became 
slightly  narrower  and  about  8\x  longer.  Again:  Small  spores  liberated 
at  12:37  were  nearly  all  at  rest  by  12:50,  all  by  12:56  (in  spring  water  at 
room  temperature  of  180  C.  a  single  sporangium  was  separated  just  before 
discharge  and  the  spores  were  liberated  in  a  drop  on  a  slide.)  On  emerging 
the  spores  swim  slowly  and  aimlessly,  changing  direction  momently  and 
coming  to  rest  in  about  15  minutes.  After  several  hours  they  emerge  and 
swim  very  actively  (more  than  three  times  as  fast  as  in  first  stage)  and 
with  a  definite  aim,  revolving  slowly.  They  are  slightly  smaller  than  in  the 
first  stage  and  have  a  slight  groove  down  most  of  one  side. 

By  examination  of  a  large  number  of  sporangia  of  all  shapes  and 
sizes  we  find  that  in  the  majority  of  cases  the  large  sporangia  produce 
the  large  spores  and  small  sporangia  (gemmae)  produce  small  spores. 
This  is  subject  to  numerous  exceptions.  As  a  rule  the  spores  of  a  single 
sporangium  are  all  of  one  size,  but  in  several  cases  we  have  seen  the  two 
sizes  in  the  same  sporangium.  Moreover,  there  are  intermediate  sizes, 
but  these  are  not  nearly  so  numerous  as  the  extremes. 

All  the  following  cultures  were  made  from  a  single  spore  culture 
(size  of  spore  not  known)  from  No.  12  of  January  30,  1913: 

On  corn  meal  agar.  Growth  good.  A  good  many  gemmae  n  chains  of  two  to  four,  a 
condition  not  found  in  water  cultures  except  very  rarely.  No  sexual  reproduction. 

On  white  of  egg  in  distilled  water.  Growth  delicate.  A  very  few  gemmae  formed,  soon 
dying.  Apparently  no  sporangia. 


38  THE  SAPROLEGNIACEAE 

On  egg  yolk  in  distilled  water.  Growth  extensive.  A  few  small  gemmae.  No  sporangia, 
apparently.  This  experiment  was  repeated  and  the  growth  was  very  strong.  A  good 
many  sporangia  of  usual  shape.  Very  many  gemmae  of  all  shapes,  most  in  chains — 
some  very  long  chain-forms,  exactly  as  in  S.  ferax. 

In  equal  parts  maltose  5%  and  peptone  .01%  solution.  Growth  very  extensive,  but 
entirely  sterile.  No  gemmae,  sporangia  or  oogonia.  Many  threads  were  spirally 
curled. 

On  corn  meal  egg  yolk  agar.  Remarkable  growth,  different  from  any  other  water  mold. 
Agar  was  covered  and  an  aerial  growth  followed  that  hid  the  agar  under  a  dense  pure 
white  cottony  mantle  cm.  thick,  some  fibers  reaching  still  higher  and  touching  the 
cover.  In  the  aerial  mass  were  a  good  number  of  pear-shaped  or  nearly  spherical 
gemmae  of  smaller  size  than  usual.  Growth  inside  the  agar  only  vegetative. 

On  corn  meal  agar.  Fine  growth  filling  dish.  Many  gemmae  of  usual  shape.  No  oogonia. 

In  egg  yolk  broth.  Growth  good,  but  not  over  an  inch  in  diameter.  Many  sporangia  were 
formed,  but  very  few  formed  spores.  Most  of  them  became  resting  sporangia  with 
undifferentiated  protoplasm.  Many  gemmae.  These  resting  parts  were  left  free  by 
the  disappearance  of  the  threads.  All  parts  smaller  than  usual. 

In  egg  yolk  broth.  Growth  very  strong  and  extensive.  Many  large  gemmae  and  sporangia. 
No  oogonia.  Sporangia  emptying  normally. 

On  yolk  of  egg  and  ant  in  distilled  water.  Very  strong  growth,  nearly  filling  dish.  Many 
large  gemmae.  Also  a  good  many  oogonia  were  formed,  but  only  near  the  ant. 

On  white  of  egg  and  ant  in  distilled  water.  Growth  abundant,  but  more  delicate  than  in 
above.  Many  gemmae,  smaller  than  above,  and  a  good  many  sporangia.  No  oogonia. 

On  ants  alone  in  distilled  water.  Growth  strong,  many  sporangia  and  gemmae,  about  as 
in  above  culture.  No  oogonia. 

On  egg  yolk  in  distilled  water.  Strong  growth  and  many  spores,  both  large  and  small. 
Many  gemmae.  No  oogonia.  Culture  soon  going  to  pieces. 

On  corn  meal  egg  yolk  agar.  Grew  well  but  did  not  send  up  any  conspicuous  growth  in 
air.  Many  oval,  round,  and  pear-shaped  gemmae  formed.  No  other  reproduction. 

On  mushroom  grub  in  distilled  water.  Grew  well.  Many  gemmae  of  all  usual  shapes  and 
many  sporangia.  All  spores  formed  were  small  ones.  A  few  very  large  undivided 
masses  had  been  ejected  as  in  most  cultures. 

On  mushroom  grub  in  distilled  water.  Two  cultures  were  made.  One  showed  apparently 
no  large  spores,  thousands  of  small  ones.  The  other  showed  a  good  many  large  spores 
also.  Nearly  all  sporangia  proliferated  as  in  Achlya.  Many  gemmae  in  each  as  usual. 
Two  other  cultures  made  a  little  later  gave  the  same  result  except  all  spores  small. 

In  5%  maltose  in  distilled  water.  Growth  vigorous,  but  entirely  vegetative.  Threads 
small.  Later  a  fair  number  of  spherical  gemmae  were  formed.  Another  culture  gave 
the  same  result  except  that  it  went  to  pieces  without  forming  any  gemmae. 

On  mushroom  grub  in  spring  water.  Growth  and  behavior  as  in  distilled  water  except  that 
many  sporangia  proliferated  repeatedly  from  within  old  ones,  exactly  as  usual  in 
Saprolegnia.  A  second  culture  gave  the  same  results.  There  were  a  few  large 
spores — not  more  than  1  in  100.  Four  years  later  (in  1918)  repeated  experiments 
were  made  with  No.  1  of  April  4,  1918,  to  test  again  the  effect  of  different  water  on 
sporangia  proliferation.  The  results  were  the  same.  In  distilled  water  most  of 
the  sporangia  proliferate  by  lateral  branching  below  as  in  Achlya ,  while  in  spring 
water  most  of  the  proliferation  is  internal  as  usual  in  Saprolegnia. 


SAPROLEGXIA 


39 


The  cultures  in  the  following  solutions  were  all  made  on  termites: 

In  .1%  KN03.  Gemmae  and  sporangia  present.  No  oogonia  or  antheridia. 

In  .1%  KH2PO4.  Growth  limited,  and  soon  dying. 

In  .1%  Na2HP04.  Growth  good.  Not  many  sporangia,  only  a  few  liberating  spores. 
A  good  many  gemmae. 

In  .1%  of  K2SO4.  Growth  good.  Gemmae  plentiful;  sporangia  few,  some  discharging, 
some  not. 

In  .1%  Ca3(P04)2.  Growth  good.  Many  gemmae.  Few  sporangia;  some  not  dis¬ 
charging. 

In  .1%  Ca(N03)2.  Growth  limited.  Few  gemmae.  No  sporangia. 

The  following  cultures  were  made  in  a  solution  consisting  of  equal 
parts  of  a  .2%  solution  of  the  salts  indicated  and  a  maltose-peptone 
solution  made  by  adding  equal  parts  of  5%  maltose  and  .01%  peptone 
solutions.  Bacteria  limited  the  growth  in  most  cases. 

In  Ca(N03)2  +  maltose-peptone  solution.  Growth  about  }4  inch  in  diameter.  No  re¬ 
production. 

In  IvN03  T  maltose-peptone  solution.  Same  result  as  in  preceding. 

In  Ca3(P04)2  +  maltose-peptone  solution.  Growth  delicate  and  rather  more  extensive 
than  in  preceding.  A  few  sporangia  formed.  A  number  of  threads  spirally  wound. 
In  KH2P04  +  maltose-peptone  solution.  Delicate  and  extensive  growth  (2  inches  in 
diameter).  No  reproduction. 

In  Na2HP04  T  maltose-peptone  solution.  No  growth. 

In  K2S04  +  maltose-peptone  solution.  Growth  about  1  inch  in  diameter.  A  very  few 
gemmae.  No  other  reproduction. 

In  y2  maltose-peptone  solution  and  >2  egg  yolk  broth.  Dense  growth  of  fine  even  threads 
Ip2  inches  in  diameter.  No  reproduction. 

The  following  experiments  were  made  to  find  the  best  method  of 
preserving  live  cultures: 

Culture  put  in  vial  on  corn  meal  agar  March  18,  1913,  was  found  to  be  dead,  December  1, 
1913- 

Culture  put  in  aquarium  jar  with  algae,  etc.,  on  laboratory  table  on  March  3,  1913.  No 
growth  could  be  obtained  from  it  when  test  was  made  September  18,  1917. 

The  following  cultures  were  made  from  No.  2  of  January  2,  1917: 

On  corn  meal  agar.  Growth  vigorous,  covering  the  plate.  A  few  sporangia,  which  did  not 
empty  their  spores.  Many  oogonia  with  eggs.  Antheridia  present  in  varying  numbers 
on  every  oogonium,  all  diclinous,  so  far  as  seen.  This  experiment  was  repeated  several 
times  with  varying  results.  A  few  sporangia  were  always  formed,  but  often  there 
was  no  sign  of  any  sexual  reproduction. 

In  haemoglobin  solution.  Vigorous  growth,  but  no  eggs  and  no  sporangia.  Repeated  this 
experiment.  Vigorous  growth.  Abundance  of  oogonia  formed,  but  eggs  went  to 
pieces  as  soon  as  formed.  A  few  sporangia  and  some  large  and  small  spores  given  off 
in  early  stage  of  growth.  Antheridia  present  on  all  oogonia. 


4° 


THE  SAPROLEGNI ACEAE 


5.  Saprolegnia  ferax  (Gruith.)  Thuret.  Ann.  .Sci.  Nat.  Bot.,  Series  3, 
14:  214,  pi.  22.  1850. 

Achlya  prolifera  Pringsh.  Nova  Acta  Acad.  C.  L.  C.  N.  C.  23:  395, 
pis.  4b- 5®*  1851* 

Saprolegnia  dioica  Pringsh.  Jahrb.  f.  wiss.  Bot.  2:  206,  pi.  22,  figs. 
1-6.  i860. 

Saprolegnia  dioica  var.  racemosa  de  la  Rue.  Bull.  Soc.  Imp.  Nat. 

Moscow  42,  1:  469.  1869  (see  Fischer,  p.  336). 

Saprolegnia  Thnreti  deBary.  Abh.  Senckenb.  naturf.  Ges.  12: 
326,  pi.  5,  figs.  1-10.  1881.  Also  in  Morph,  u.  Phys.  der  Pilze, 
IV  Riehe:  102.  1881. 

Saprolegnia  bodanica  Maurizio.  Jahrb.  f.  wiss.  Bot.  29:  107,  pi.  2, 
figs.  52-59a.  1896. 

?  Saprolegnia  esocina  Maurizio.  Jahrb.  f.  wiss.  Bot.  29:  82,  pi.  1, 
figs.  4-17.  1896. 


Plates  ii  and  12 

Hyphae  moderately  stout  and  vigorous,  irregular,  sparingly  branched 
below.  Sporangia  plentiful,  only  slightly  enlarged,  typically  wavy  and 
bent  and  of  unequal  diameter,  often  tapering  upward,  rarely  almost 
cylindrical,  often  proliferating  laterally  from  below  old  ones;  zoospores 
about  9^  in  diameter.  Gemmae  not  very  abundant,  more  or  less  elon¬ 
gated  usually,  but  varying  to  bulbous,  or  pyriform  and  sometimes  jointed. 
There  is  a  strong  tendency  to  the  formation  of  long  tapering  tips  on 
the  ends  of  stout  threads,  the  ends  of  which  are  later  cut  off  as  rejected 
tips  of  irregularly  tapering  gemmae  below.  In  such  cases  the  gemma 
opens  later  by  basal  protuberance  as  is  also  usually  the  case  even  when 
no  tip  is  cut  off.  Oogonia  numerous,  varying  in  diameter  from  37  to 
97^,  the  wall  only  about  1 .3— 1 .6p.  thick,  but  with  numerous  conspicuous 
pits,  which  are  about  4-5~5-5[J'  in  diameter;  either  lateral  on  stalks  which 
are  usually  short  and  frequently  curved,  or  terminal  on  the  main  branches, 
sometimes  intercalary,  but  not  in  chains;  spherical  to  slightly  oval  with  a 
basal  neck,  which  is  often  curved;  not  rarely  formed  inside  of  empty  spor¬ 
angia,  and  then  cylindrical;  thread-like  extensions  of  the  oogonia,  con¬ 
taining  a  single  row  of  elliptic  eggs,  are  not  rare.  Eggs  centric,  1-20, 
mostly  4-16,  the  diameter  24-30.5^,  (rarely  as  small  as  I4.8[a  or  as  large 
as  33.8[x),  the  greater  number  about  26[j,,  extremes  sometimes  occur¬ 
ring  in  the  same  oogonium.  Antheridial  branches  short,  stout,  mostly 
androgynous,  present  in  nearly  all  cultures  in  varying  number,  usually 
on  about  10-15%  of  the  oogonia,  but  the  number  of  oogonia  furnished 
with  them  varies  from  none  to  98%,  depending  on  the  medium  used. 
The  antheridia  arise  as  a  rule  from  the  same  main  strands  that  bear 
their  oogonia,  but  often  also  from  the  oogonial  stalks,  and  in  the  latter 
case  usually  applying  themselves  not  to  their  own  but  to  nearby  oogonia, 
either  from  the  same  or  another  strand.  Antheridia  usually  cut  off, 
short  and  tuberous,  not  more  dense  than  the  threads;  fertilizing  tubes 
suppressed  or  very  rare. 


PLATE  11 


PLATE  11 
Saprolegnia  ferax 

Fig.  I.  Sporangia  containing  a  cylindrical  oogonium.  X  447. 

Fig.  2.  Proliferation  through  old  sporangia.  X  247. 

Fig.  3.  Habit  of  fruiting.  The  stalks  of  the  two  upper  oogonia  are  hidden.  X  108. 

Fig.  4.  Cylindrical  oogonium,  with  some  eggs  of  abnormal  shape.  X  447. 

Fig.  5.  Sporangium  with  long  papilla.  X  167. 

Fig.  6.  Gemmae.  X  102. 

Fig.  7.  Gemma  with  an  oogonium  attached.  X  447. 

Fig.  8.  Oogonium  partly  filled  with  ripe  eggs,  and  showing  an  ingrowing  tube  from  below. 
X  447- 

Fig.  9.  Spore  in  first  swimming  stage.  X  720. 

Fig.  10.  Oogonium  with  antheridia.  X  417. 

Fig.  II.  A  cylindrical  oogonium  with  a  spherical  protuberance.  X  447. 

Fig.  12.  Sporangia  renewed  both  as  in  Achlya  and  in  Saprolegnia.  X  167. 


PLATE  11 


SAPROLEGNIA  FERAX. 


PLATE  12 


'  .  v  ' 

'*X  \  "" 


A  " 


SAPROLEGNIA  FERAX.  x  6 


SAPROLEGNIA 


41 


Distinguished  by  conspicuous  and  mostly  numerous  pits,  by  the 
occurrence  in  most  cultures  of  cylindrical  oogonia,  by  the  frequently  curved 
stalks  and  necks  of  the  oogonia,  and  by  the  scarcity  of  antheridia,  which 
are  mostly  androgynous  and  borne  on  short,  simple  or  little  branched 
stalks. 

Common  in  springs  and  branches,  as  Arboretum  spring  and  brook, 
Battle’s  branch,  etc.,  appearing  in  12.5%  of  all  Chapel  Hill  collections 
between  February  15,  1912,  and  December  12,  1913  (see  table);  also 
many  times  since. 

Distribution:  Chapel  Hill,  N.  C.,  Kentucky,  Missouri,  Massachu¬ 
setts,  Wisconsin,  Michigan. 

For  other  illustrations  see  Pringsheim  (’73),  pi.  18,  figs.  5  and  11; 
W.  G.  Smith,  (’78),  2  unnumbered  plates;  Minden  (’12),  figs,  ib-c  on 
p.  520;  Maurizio  (’96),  pi.  1,  figs.  28-36;  Humphrey  (’92),  pi.  16,  figs. 
43-45;  Lechmere  (’11a),  figs.  2-4;  Klebs  (’99),  figs.  1-2  (or  S',  mixta); 
Rothert  (’88),  pi.  10,  figs.  1-13;  Istvanffi  (’95),  pi.  35,  figs.  14-18;  Dangeard 
(’90),  pi.  5,  figs.  6-27. 

Minden  (’12,  p.  521)  has  described  two  forms  of  S.ferax  as  follows: 

Form  1.  “ Sporangia  more  inflated  or  spindleform  than  cylindrical, 

often  irregular  in  sections  and  with  tapering  tips;  oogonia  terminal,  often 
on  long,  bent  stalks,  typically  spherical,  if  indeed  at  times  with  a  cylin¬ 
drical  neck,  very  rarely  cylindrical;  antheridia  very  rare,  but  no  more 
so  than  in  the  typical  form. 

Form  2.  “  Like  the  typical  except  that  the  oogonia  are  borne  mostly 

on  the  ends  of  very  short  side  branches  in  regular  racemose  arrange¬ 
ment,  which  according  to  Fischer  should  not  be  the  case  in  the  typical 
form.  Many  of  the  large  oogonia,  which  contain  numerous  eggs,  are 
cylindrical  in  empty  sporangia.” 

It  is  obvious  that  this  Form  2  is  very  like  our  Chapel  Hill  plant, 
and  it  is  also  probably  not  different  from  Fischer’s  form  in  spite  of  sup¬ 
posed  discrepancies.  Humphrey’s  slides  show  a  plant  similar  to  ours. 
It  is  also  to  be  noted  that  neither  Humphrey  nor  we  find  the  large  number 
of  eggs,  up  to  40-50,  in  an  oogonium  which  are  recorded  by  deBary  and 
other  European  writers  who  seem  to  have  copied  from  him  (Fischer, 
Minden).  Pringsheim’s  figures  5,  pi.  17;  and  3,  pi.  18,  in  his  Jahrb.  f. 
wiss.  Bot.  9,  1873,  look  suspiciously  like  our  A.  ferax,  though  labelled 
by  him  Achlya  polyandra. 

Saprolegnia  esocina  Maurizio  is  so  near  this  species  as  perhaps  to 
fall  well  within  its  range  of  variation.  It  is  described  as  differing  from 
the  typical  S.  Thureti  in  the  size  of  the  eggs,  which  are  21.5-25^  in  diam- 


42 


THE  SAPROLEGNIACEAE 


eter,  one  to  30  in  an  oogonium,  and  in  absence  of  oogonia  in  chains.* 
Antheridia  scarce,  only  two  seen  and  these  diclinous.  Found  on  a  living 
pike  in  Switzerland.  This  may  be  the  same  as  S.  lapponica  (see  p.  73), 
but  that  is  said  rarely  to  have  oogonia  terminating  the  main  branches. 

Saprolegnia  bodanica  Maurizio  is  another  plant  that  seems  almost 
exactly  like  our  Chapel  Hill  S.ferax:  Threads  slender,  main  ones  31-474 
thick,  often  with  cellulose  grains  which  may  stop  up  the  small  threads 
as  in  Le  ptomitus .  Oogonia  racemose,  rather  seldom  intercalary,  never 
in  chains;  wall  thin,  colorless, with  numerous  small  pits;  oogonia  54-934 
thick,  the  oblong  ones  88x1084.  Eggs  23.5-314  thick,  4-30+  in  an 
oogonium.  No  antheridia. 

Saprolegnia  ferax  cannot  be  limited  to  forms  without  antheridia. 
DeBary  admits  the  presence  of  some  antheridia  as  does  Humphrey  also, 
but  it  would  appear  from  the  work  of  Pieters  and  myself  that  antheridia 
are  frequently  present  on  as  many  as  10-15%  °f  the  oogonia.  Pieters 
(Mycologia  7:  310.  1915)!  has  found  that  in  his  strains  from  Ann  Arbor 
grown  on  fly  at  room  temperature  and  in  cooler  temperature  (120— 150  C.) 
the  number  of  oogonia  with  antheridia  varied  from  0-19%  (see  his  pi.  170, 
fig.  1).  For  other  experimental  work  in  this  species  see  Pieters  (’15b). 
In  his  studies  on  the  physiology  of  Saprolegniaceae  (Ann.  Bot  22:  361. 
1908)  Kauffman  supposes  a  strain  of  his  from  Ann  Arbor  to  be  S.  mixta 
because  it  contained  a  few  antheridia,  1  or  2  per  cent  normally.  This 
must  be  considered  S.  ferax  if  the  latter  and  N.  mixta  are  to  be  kept 
separated  at  all.  In  experiments  with  his  strain  he  increased  the  pro¬ 
portion  of  antheridia-bearing  oogonia  to  25%  both  in  leucin  +  potassium 
sulphate  and  in  haemoglobin  +  potassium  nitrate.  In  haemoglobin + 
calcium  nitrate,  on  the  other  hand,  there  were  no  antheridia  on  the 
abundant  oogonia.  For  cytological  data  see  Dangeard  (’90),  p.  101  and 
(’16),  p.  87. 

Trow  has  shown  that  in  material  that  he  calls  S.  Thureti  or  S.  mixta, 
depending  on  the  absence  or  presence  of  antheridia,  the  unfertilized  eggs 
are  uninucleate  as  in  other  species  and  are  without  nuclear  fusions  in 
his  opinion  (’95,  p.  637).  In  all  respects  except  fertilization  the  cyto¬ 
logical  phenomena  are  alike.  See  S.  mixta  for  some  detail. 

*01  the  typical  form  of  S.ferax  Maurizio  says  the  oogonia  are  often  in  chains,  eggs  3 
to  about  50,  23-26.5(0.  in  diameter  (Jahrb.  f.  wiss  Bot.  29:  93.  1896).  Minden  says  (1.  c. 
p.  521)  the  oogonia  are  seldom  intercalary  in  chains,  the  eggs  20-274  in  diameter,  not  rarely 
over  40-50  in  an  oogonium.  Oogonia  in  chains  are  not  mentioned  by  deBary,  Pringsheim, 
Humphrey  or  Fischer  (the  latter  giving  the  eggs  as  20-27(0,  thick).  To  separate  new  species 
on  absence  of  such  chains  would  seem,  therefore,  to  be  poor  judgment.  It  may  be  said 
that  Maurizio’s  work  gives  many  indications  of  inferiority. 

fAlso  listed  in  Ann.  Mich.  Acad.  Sci.  17:  195.  1915,  as  S.  Thureti. 


SAPROLEGNIA 


4A 


Davis  (’03)  worked  with  a  plant  that  would  better  have  been  called 
5.  ferax  than  S.  mixta ,  as  it  bore  no  antheridia  at  the  time  he  was  put¬ 
ting  up  his  preparations.  His  results  were  in  general  the  same  as  Claus- 
sen’s  for  S.  monoica  and  Trow’s  for  S.  mixta  and  S.  diclina,  aside  from 
fertilization  phenomena  (which  were  of  course  absent)  and  with  the  excep¬ 
tion  of  certain  detailsof  the  structure  and  division  of  the  nucleus,  in  which 
he  corrected  Trow  in  several  points.  His  attacks  on  Trow’s  conclusion 
that  fertilization  did  occur  where  antheridia  were  present  have  proved 
since  to  be  entirely  unjustified.  Davis  found  four  chromosomes  in  the 
division  in  the  oogonium,  a  matter  of  much  interest  in  this  partheno- 
genetic  form,  as  Claussen  found  the  number  to  be  10-14  in  S-  monoica 
where  fertilization  occurs.  The  spindle  is  entirely  intranuclear.  The  eggs 
are  frequently  binucleate  and  rarely  trinucleate. 

The  pioneer  work  in  the  physiology  of  this  group  was  done  by  Klebs 
who  worked  on  a  plant  that  normally  on  flies  in  water  showed  only  10- 
20%  of  oogonia  with  antheridia.  He  considered  the  plant  S.  mixta , 
but  according  to  our  rule  it  would  fall  under  S.  ferax.  For  this  reason 
we  refer  here  to  his  conclusions  although  we  do  not  know  that  his  plant 
really  was  S.  ferax.  The  important  results  of  his  work  are  summarized 
by  him  as  follows  (translated)  (’99,  p.  582)  :* 

1.  Uninterrupted  continuous  growth: — in  all  good  nutrient  media,  so  long  as  fresh  unaltered 

nutrient  is  present,  e.  g.,  in  water  with  peas,  in  weak  meat  extract  (1-2%),  in  gelatin 
with  peptone,  in  mixtures  of  water  with  albumen,  casein,  etc. 

2.  Prompt  and  complete  transformation  of  the  mycelium  into  sporangia  and  zoospores: — - 

by  placing  a  well-nourished  mycelium  in  fresh  water. 

3.  Growth  with  continuous  formation  of  zoospores: — in  very  weak  solution  of  certain  nutri¬ 

ents,  e.  g.,  0.005%  haemoglobin,  also  in  mycelium  on  agar-albumen  jelly  that  is  put  in 
running  water. 

4.  Active  formation  of  oogonia  with  limited  growth: — by  putting  a  well  nourished  myce¬ 

lium  in  agar-agar. 

5.  Active  growth,  then  active  formation  of  oogonia:— 

(a)  oogonia  with  antheridia: — in  solution  of  leucin  (0.1%)  with  tricalcium  phosphate 
(0.1%). 

(b)  oogonia  without  antheridia: — in  solution  of  haemoglobin  (0.05-0. 1%). 

6.  Growth,  then  formation  of  sporangia,  then  of  oogonia: — by  placing  the  mycelium  in 

water  from  gelatin-meat  extract;  or  by  culture  on  dead  insect  in  water. 

7.  Growth  and  simultaneous  formation  of  sporangia  and  oogonia: — in  water  with  some 

fibrin  or  syntonin. 

8.  Growth,  then  formation  of  oogonia  and  later  sporangia: — -after  strong  nutrition  ot  the 

mycelium  transfer  to  0.01%  haemoglobin. 

9.  Active  formation  of  gemmae: — by  putting  a  well  nourished  mycelium  in  0.6%  trical¬ 

cium  phosphate,  or  1%  sodium  chloride,  etc. 

*An  even  more  condensed  and  somewhat  modified  restatement  ot  his  results  is  made 
by  Klebs  in  his  Willkurrliche  Entwickelungsanderungen  bei  Ptlanzen,  p.  41-  Jcna>  I9°3- 


44 


THE  SAPROLEGXIACEAE 


io.  Growth  with  sporangia,  then  gemmae;  or  growth  with  oogonia,  then  gemmae;  or 
growth  with  sporangia  and  oogonia  and  then  gemmae:— in  the  items  3,  5  and  6  above, 
when  the  culture  is  continued  to  the  complete  exhaustion  of  the  nutrient  material. 

General  conclusions  in  regard  to  conditions  for  the  formation  of 
oogonia  and  antheridia  are  summarized  as  follows  (1.  c.,  p.  566): 

1.  In  a  mycelium  which  is  constantly  given  fresh  nourishment  no  oogonia  are  ever  formed. 

Young,  just  formed  oogonia  were,  by  means  ol  fresh,  soluble  food,  induced  to  vege¬ 
tative  growth.  The  old  were,  however,  killed. 

2.  If  a  strongly  nourished  mycelium  is  changed  to  a  medium  of  low  nutritive  value  (in 

which  the  formation  of  sporangia  is  rare  or  absent)  oogonia  are  formed  in  a  few  days. 

3.  In  a  good  soluble  food,  preferably  at  such  concentration  that  the  sporangia  cannot 

be  formed,  the  mycelium  begins  to  form  oogonia  as  soon  as  the  solution  is  chemically 
changed  on  account  of  its  growth,  and  has  lost  its  nutritive  value. 

4.  The  formation  of  oogonia  is  particularly  encouraged  through  phosphate,  which  is 

likewise  necessary  to  the  formation  of  the  antheridia.  In  a  soluble  food  that  is 
poor  in  phosphate  oogonia  are  formed,  but  no  antheridia;  particularly  abundant  are 
such  oogonia  in  a  pure  solution  of  haemoglobin. 

5.  In  many  soluble  foods,  for  example  in  peptone,  gelatine,  etc.,  are  excreted  certain  prod¬ 

ucts  of  assimilation  of  the  mycelium  which  hinder  the  formation  of  oogonia. 

All  of  the  following  cultures  were  made  by  us  from  a  single 
spore  culture  of  Xo.  10  of  January  15,  1913: 

In  equal  parts  of  5%  maltose  and  .01%  peptone.  The  solution  was  inoculated  with 
swimming  spores  on  February  14,  1913.  By  the  18th  or  19th  the  culture  had  covered 
the  petri  dish,  and  had  formed  a  large  number  of  oogonia  with  perfect  eggs.  Oogonia 
were  somewhat  inflated  with  eggs  not  filling  the  cavity;  eggs  of  usual  number,  vary¬ 
ing  in  size  from  15.5-27.7fi.,  averaging  about  24.410..  This  is  smaller  on  average  than 
other  cultures.  Of  scores  of  oogonia  examined  only  one  or  two  had  antheridial 
branches  attached,  and  no  antheridia  were  cut  off.  No  sporangia  were  formed,  and 
therefore  all  oogonia  were  spherical.  This  is  the  only  Saprolegnia  that  forms  normal 
oogonia  and  eggs  in  this  medium. 

On  ant  in  rain  water.  Sporangia  abundant.  Oogonia  plentiful,  heavily  pitted,  nearly  all 
spherical,  and  containing  1-6  eggs,  most  with  2  or  4  eggs.  Many  oogonia  do  not 
perfect  the  eggs.  Scattering  gemmae.  Repeated  this  experiment  with  same  results 
except  that  there  were  more  cylindrical  oogonia.  Almost  no  antheridia.  It  is 
evident  that  the  purer  the  water  the  fewer  the  antheridia. 

On  ant  in  spring  water.  Abundant  sporangia.  Oogonia  very  abundant,  nearly  all 
spherical,  a  few  cylindrical;  pits  abundant:  oogonia  very  healthy,  all  maturing  the 
eggs,  which  vary  from  1-12,  mostly  1-6.  Antheridia  on  probably  33%  of  the 
oogonia.  Very  few  gemmae.  Repeated  this  experiment  with  same  results,  except  that 
there  were  more  cylindrical  oogonia. 

On  ant  in  distilled  water.  Growth  shorter  and  stouter  than  in  the  two  preceding  cultures. 
Sporangia  abundant  and  stout.  Oogonia  very  abundant  and  large,  with  thick,  heavily 
pitted  walls,  spherical  or  cylindrical,  the  proportion  of  cylindrical  ones  being  much 
larger  than  usual,  comprising  about  yi  of  all,  very  healthy  and  maturing  all  eggs, 
cylindrical  ones  generally  with  4  eggs,  often  with  2  or  3,  spherical  ones  sometimes  with 
12  eggs,  but  generally  from  1-8.  The  eggs  of  this  culture  average  larger  than  in  mal¬ 
tose-peptone,  varying  from  14.8-33.34,,  averaging  about  25.84..  The  few  eggs  that 
reach  the  largest  size  are  only  one  to  the  oogonium.  The  smallest  size  may  occur  in  an 


SAPROLEGNIA 


45 

oogonium  with  much  larger  ones.  Apparently  no  antheridia.  Repeated  above  cul¬ 
ture  with  same  results. 

On  yolk  of  egg.  Growth  abundant  and  extensive.  A  good  many  sporangia  and  a  vast 
number  of  oogonia  formed.  A  very  few  oogonia  (probably  not  more  than  I  in  ioo) 
had  an  antheridium  attached.  Antheridia  androgynous  or  diclinous.  No  oogonia 
inside  sporangia,  hence  no  cylindrical  ones. 

On  corn  meal  agar.  The  whole  petri  dish  covered  and  within  the  agar  a  great  number  of 
fine,  healthy  oogonia  were  formed,  with  perfect  eggs  of  normal  size.  No  antheridia. 
A  few  small  gemmae  formed.  This  is  our  only  Saprolegnia  that  forms  oogonia  in  this 
medium  except  S.  monoica  and  in  that  case  many  of  the  oogonia  are  inflated  and  with 
no  eggs. 

On  corn  meal  egg  yolk  agar.  Fine  growth,  covering  agar.  Very  many  oogonia,  with  fine 
eggs.  Antheridia  on  not  more  than  5%. 

In  the  following  cultures  a  .1%  solution  of  the  salts  in  distilled 
water  was  used,  and  the  food  material  is  yolk  of  egg,  unless  otherwise 
indicated : 

In  KNO3.  Growth  delicate,  but  healthy.  Many  normal  but  small  oogonia,  about  one- 
third  with  diclinous  antheridial  branches.  A  few  sporangia  formed. 

In  KH2PO4.  Growth  strong  and  healthy.  Sporangia  present,  but  scattering,  their  spores 
emerging  and  dispersing  slowly.  Many  normal  oogonia,  none  cylindrical,  the  great 
majority  with  one  or  more  antheridial  branches  about  them,  which  are  nearly  all  dicli¬ 
nous  (not  one  in  a  hundred  androgynous),  no  antheridia  cut  off  from  the  branches. 

In  Na2HP04.  Many  sporangia,  and  very  many  normal  oogonia,  nearly  all  (at  least  98%) 
with  antheridial  branches,  of  diclinous  origin;  occasionally  an  antheridium  was  cut  off. 

In  K2SO4.  Growth  strong  and  healthy.  Sporangia  few,  emptying  as  usual.  Oogonia 
very  abundant,  with  normal  and  good  eggs.  In  the  main  mass  of  the  culture  there 
were  antheridial  threads  on  at  least  90%  of  the  oogonia,  a  good  many  with  antheridia 
cut  off.  No  gemmae. 

In  Ca3(P04)2.  Growth  strong  and  vigorous.  A  good  many  sporangia.  Very  abundant 
oogonia,  maturing  all  eggs.  Those  in  bulk  of  culture  with  95%  or  more  furnished  with 
antheridia;  on  margin  a  much  smaller  proportion  have  antheridia.  Scattering  gemmae. 

In  Ca(N03)2.  Growth  more  delicate  than  in  others  of  this  series,  but  about  same  extent. 
Oogonia  much  fewer  than  in  preceding,  all  with  good  eggs.  Even  in  the  denser  mass 
of  culture  not  more  than  10%  with  antheridia  and  very  few  with  antheridia  near  the 
periphery.  Many  oogonia-like  gemmae. 

The  following  experiments  were  made  to  test  the  vitality  of  the  eggs: 

A  culture  on  corn  meal  agar  with  fine  oogonia  and  eggs  was  allowed  to  dry  out  to  a  sufficient 
extent  to  collapse  the  gemmae.  Water  was  put  on  and  it  was  examined  at  intervals. 
The  eggs  went  to  pieces  soon.  They  had  been  killed  by  the  desiccation. 

Eggs  which  had  been  resting  for  about  four  months  were  put  in  fly  extract  on  September 
13,  1912,  in  two  watch  glasses.  One  had  a  cover  glass  put  over  the  eggs  to  exclude 
air.  Kept  until  September  24th.  Neither  showed  germination  though  the  eggs 
seemed  perfectly  good. 

Experiments  to  test  best  method  of  preserving  live  cultures: 

Culture  put  in  vial  on  corn  meal  agar,  March  18,  1 9 1 3»  was  found  to  be  dead  December  I, 
I9CV 

Culture  put  in  aquarium  jar  with  algae  in  laboratory  on  March  3,  1 9 1 3>  was  tested  in 
jar  on  September  18,  1917,  but  no  growth  appeared. 


46  THE  SAPROLEGNIACEAE 

6.  Saprolegnia  mixta  deBary.  Bot.  Zeit.  41:  38  and  54.  1883. 

?  S.  heterandra  Maurizio.  Jahrb.  f.  wiss.  Bot.  29:  87,  pi.  1,  figs. 
18-27.  1896. 

?  S.  dioica  Schroet.  Jahrb.  d.  Schles.  Gesell.  f.  vaterl.  Cultur,  1869, 
47:  143.  1870. 

As  originally  defined  by  deBary  this  species  was  placed  in  the  Ferax 
group  and  separated  from  A.  ferax  on  the  one  hand  by  having  antheridia 
on  about  fifty  per  cent  of  the  oogonia  instead  of  none  or  a  very  few, 
by  the  swollen  oogonia  with  fewer  eggs,  and  by  the  more  delicate  my¬ 
celium;  on  the  other  hand  it  was  distinguished  from  A.  monoica  by  fewer 
antheridia,  more  numerous  and  often  larger  pits  in  the  oogonia,  and 
by  the  weaker  mycelium.  Saprolegnia  hypogyna,  with  very  similar  oogo¬ 
nia,  is  easily  separated  from  all  others  by  the  sub-oogonial  cell. 

In  recent  years  there  has  been  great  confusion  in  regard  to  A.  mixta , 
and  subsequent  collections  have  shown  pretty  clearly  that  this  species 
and  probably  also  S.  ferax  are  composed  of  a  number  of  forms,  them¬ 
selves  variable,  of  which  deBary  had  only  one.  In  a  very  sensible  dis¬ 
cussion  of  this  subject  Pieters  (Mycologia  7:  307.  1915)  has  concluded 
that  from  what  is  known  at  present  it  is  best  to  consider  as  A.  mixta 
those  forms  with  weak  mycelium  and  with  antheridia  on  one-half  or 
more  of  the  oogonia,  while  to  A.  ferax  should  be  referred  those  with 
stronger  mycelium  and  only  a  small  number  of  antheridia  on  fly  cul¬ 
tures  at  a  temperature  of  12-15  degrees  centigrade.  Saprolegnia  monoica 
will  still  include  only  those  forms  with  antheridia,  usually  androgynous, 
on  every  oogonium  in  all  ordinary  natural  media.  To  these  conclusions 
we  agree  (if  S.  mixta  is  to  be  retained  at  all),  but  it  is  not  to  be  supposed 
that  this  convenient  arrangement  will  put  an  end  to  all  confusion  in  so 
various  a  set  of  forms,  or  that  it  adequately  expresses  the  complexity  of 
the  group. 

To  show  still  further  the  frail  basis  on  which  this  species  stands 
we  have  but  to  refer  to  the  most  recent  monographs  of  the  family  by 
Minden,  who  says  that  “A.  mixta  would,  indeed,  have  to  be  united  with 
S.  Thureti  [A.  ferax]  had  not  deBary  asserted  its  constancy  over  a  long 
period.”  (Krypt.  FI.  Mark  B.  5:  519.  1912).  From  our  own  experience 

we  would  not  hesitate  to  reduce  S.  mixta,  and  retain  it  only  in  deference 
to  the  opinion  of  deBary  and  Pieters  (but  see  remarks  below  as  to  the 
plant  Pieters  observed). 

By  applying  the  above  rules  we  find  that  we  have  secured  several 
times  in  Chapel  Hill  and  once  in  Hartsville,  S.  C.,  forms  that  can  be 
referred  to  S.  mixta.  We  do  not  illustrate  these  forms,  as  the  drawings 
could  not  be  distinguished  from  similar  ones  taken  from  A.  ferax.  Of  these, 
No.  1  of  November  2,  1916,  may  be  described  as  follows: 


SAPROLEGNIA 


47 


Growth  moderately  strong  (not  so  delicate  and  more  extensive 
than  in  S.  delica ),  sporangia  long,  cylindrical,  repeatedly  proliferating, 
spores  i o-I2;j.  thick.  Gemmae  typically  elongated  rod-shaped,  sausage¬ 
shaped,  pyriform,  or  oval,  not  often  spherical,  usually  in  chains.  Oogonia 
spherical  to  oval,  moderately  plentiful  (not  nearly  so  abundant  as  in 
6".  delica),  borne  on  short  lateral  stalks,  or  terminal,  or  rather  infre¬ 
quently  intercalary,  with  or  without  a  conspicuous  neck;  wall  not  very 
thick,  about  1.8^,  with  numerous  conspicuous  pits  (the  small  ones  with 
few)  which  are  about  4. 5-6. 5^  in  diameter;  eggs  centric,  20-30^  thick, 
most  about  24-25^.,  often  oval  from  pressure,  1-20,  mostly  4-10,  not  so 
numerous  or  so  nearly  filling  the  oogonium  as  is  usual  in  S.  jerax.  An- 
theridial  branches  short,  arising  usually  from  main  branches  near  the 
oogonia  and  running  to  nearby  oogonia  either  on  the  same  thread  or  on 
others  near,  occurring  on  about  40%  or  more  (not  on  all)  of  the  oogonia 
on  flies  or  grubs. 

Found  three  or  four  times  in  Chapel  Hill,  as  in  Arboretum  spring 
(No.  1  of  November  2,  1916),  and  from  Bowlin’s  Creek,  under  bridge 
on  Durham  road  (Nos.  7  and  8  of  November  16,  1917). 

Occurrence  in  America  (of  the  species  in  all  reported  forms):  Chapel 
Hill,  N.  C.,  Hartsville,  S.  C.,  Mississippi,  Pennsylvania,  Louisiana, 
Michigan.  DeBary  once  found  the  species  on  sick  fish  (1888,  p.  617). 
For  other  illustrations  see  Humphrey,  pi.  16,  figs.  40-42;  Minden  (’12), 
figs,  id  and  ii  on  p.  520. 

As  will  be  seen  from  above,  our  form  agrees  as  well  with  deBary’s 
description  as  could  be  expected.  Especially  is  this  true  in  regard  to 
the  rather  few  eggs  which  do  not  so  nearly  fill  the  oogonium  as  usual 
in  X.  ferax  (but  the  latter  also  varies  to  similar  oogonia).  In  our  Nos.  7 
and  8  of  November  16,  1917,  the  number  of  oogonia  with  antheridia 
when  grown  on  grubs  was  about  40%,  while  in  No.  1  of  November  2, 
1916,  the  number  was  around  90%. 

Humphrey  describes  his  plants  as  having  antheridia  “absent  from 
a  part,  sometimes  from  a  large  part  of  the  oogonia.” 

Kauffman  has  found  in  Michigan  a  form  of  this  species  which  he 
cultivated  in  various  media  and  has  described  as  follows  (Ann.  Bot.  22: 
367.  1908):* 

“Hyphae  rather  slender;  zoosporangia  nearly  cylindrical.  Oogonia 
with  rather  thick  walls,  terminal,  intercalary  or  lateral,  flask-shaped, 
rarely  spherical,  the  lateral  on  short  oogonial  branches;  pits  medium 
to  large,  rather  numerous  but  not  easily  seen;  antheridial  branches  usually 
androgynous  when  the  oogonium  is  lateral,  diclinous  when  the  oogonia 
are.  terminal  or  intercalary,  long  and  slender  when  diclinous,  short  and 
slender  and  not  coiled  when  androgynous;  antheridia  on  75  per  cent  to 
90  per  cent  of  the  oogonia,  long,  subcylindrical,  not  very  profuse  on  a 


*  Also  noted  in  Ann.  Mich.  Acad.  Sci.  8:  27.  1905. 


48 


THE  SAPROLEGNIACEAE 


single  oogonium,  often  only  one  present.  Oospores  up  to  15  and  20 
in  an  oogonium,  average  diameter  24  microns,  with  rather  thick  walls.” 

Pieters  (1.  c.)  found  that  in  two  collections,  one  from  Germany 
and  one  from  Ann  Arbor  that  he  considered  .S.  mixta ,  there  were  an- 
theridia,  usually  of  diclinous  origin,  on  at  least  90%  of  theoogonia;  the 
mycelium  being  flaccid  and  delicate,  the  pits  while  present  less  promi¬ 
nent  than  in  S.  ferax.  These  characters  are  suspiciously  like  our  S. 
delica  and  it  seems  to  us  rather  likely  that  Pieters  had  that  species 
and  not  S.  mixta  as  here  considered.  We  cannot  think  that  S.  delica  is 
deBary’s  A.  mixta ,  as  he  emphasizes  the  close  resemblance  of  the  latter 
to  S.  ferax  and  S.  monoica ,  and  they  are  very  different  from  S.  delica. 
Particularly  is  this  true  in  regard  to  the  oogonia,  which  are  thin-walled 
and  with  few  and  inconspicuous  pits  in  the  latter,  while  in  the  Ferax 
group  the  walls  are  thicker  and  with  far  more  abundant  and  conspicuous 
pits.  Most  conspicuously  is  this  true  for  S.  ferax,  and  deBary  says  that 
the  oogonial  structure  of  A.  mixta  is  most  like  that  of  S.  ferax,  with  the 
pits  often  very  large.  This  would  never  do  for  S.  delica.  Moreover, 
the  often  very  long  and  preponderatingly  diclinous  antheridial  branches 
of  A.  delica  are  very  unlike  those  of  the  Ferax  group. 

Trow  (’95)  finds  fertilization  to  occur  in  case  antheridia  are  present. 
He  worked  on  material  not  certainly  pure  and  called  it  A.  ferax  when 
antheridia  were  absent  and  A.  mixta  when  they  were  in  part  present. 
His  conclusions  covering  work  on  both  S.  mixta  and  A.  diclina  ( S .  dioica) 
may  be  condensed  as  follows  (in  so  far  as  we  think  them  correct) :  The 
vegetative  nucleus  has  a  distinct  membrane,  with  chromatin  material 
and  a  linin  network;  it  divides  repeatedly  and  when  sporangia  are  formed 
enough  nuclei  enter  to  furnish  one  for  each  spore,  no  division  or  fusion 
taking  place  in  the  sporangia.  The  oogonium  receives  many  nuclei  which 
divide  once  within  it  and  form  about  20  times  more  than  are  necessary 
to  supply  the  eggs  with  one  each;  the  excess  degenerate.  Most  of  the 
nuclei  in  the  antheridia  and  fertilizing  tubes  also  degenerate.  A  single 
male  nucleus  enters  the  egg  and  approaches  the  egg  nucleus,  but  does 
not  fuse  with  it  completely  until  a  late  stage.  On  germination  the  fusion 
nucleus  divides  to  form  a  number  which  become  the  nuclei  of  the  result¬ 
ing  zoospores.  Trow  was  misled,  in  this  paper,  as  to  the  structure  of 
the  nucleus,  the  number  of  chromosomes  and  the  method  of  division. 
See  under  S.  ferax  for  Davis’s  work  on  a  plant  closely  related  to,  if  not 
the  same  as,  S.  mixta. 

Maurizio  describes  in  some  detail  a  plant  he  took  for  S.  mixta  (1895, 
p.  11,  figs.  1-3),  but  in  it  the  antheridia,  which  were  present  on  about 
a  third  of  the  oogonia,  were  borne  always  (?)  on  stalks  arising  from  the 


SAPROLEGNIA 


49 


oogonial  stalks.  The  oogonia  were  heavily  pitted,  about  35.5x108.yj. 
thick;  the  eggs  up  to  40,  with  a  diameter  of  22.5-27. 5^. 

In  his  pioneer  work  on  the  response  to  various  media  in  this  group 
Klebs  studied  a  plant  that  he  regarded  as  A.  mixta,  although  on  a  natural 
substratum,  as  flies  in  water,  it  produced  constantly  only  10—20%  of 
oogonia  with  antheridia.  For  a  summary  of  his  important  results  see 
under  5.  ferax,  where,  according  to  our  rule,  it  is  to  be  presumed  that 
Klebs ’s  strain  should  be  placed.  For  experiments  on  the  behavior  of  the 
spores  of  A.  mixta  under  various  chemical  stimuli  see  Muller  (’n). 

Sap? olegnia  heterandra  iMaurizio  is  so  near  A.  mixta  as  to  be  best  treated 
as  a  form  of  it,  although  Maurizio  places  it  nearest  S.  torulosa.  It  may 
be  briefly  described  as  follows:  Antheridia  on  about  half  the  oogonia, 
androgynous  or  diclinous.  Eggs  23.5~28[j.  in  diameter,  1-40  in  an  oogo¬ 
nium,  usually  4—I°!  germinating  in  60  days  by  a  short  germ  tube;  oogo¬ 
nia  arranged  very  variously  but  not  in  chains;  pits  not  numerous  and 
of  medium  size. 

According  to  Humphrey,  what  Schroeter  (’89)  took  to  be  S.  ferax  is 
more  like  his  (Humphrey’s)  S.  mixta.  In  such  case  S.  dioica  Schroeter 
(’69,  p.  143),  listed  without  description,  is  also  S.  mixta,  as  Schroeter 
later  (’89)  quotes  it  as  a  synonym  of  his  5.  ferax. 

7.  Saprolegnia  monoica  Pringsheim.  Jahrb.  f.  wiss.  Bot.  1:  292,  pis. 
19  and  20.  1858. 

?  S.  dioica  Pringsh.  Jahrb.  f.  wiss.  Bot.  2:  266.  i860.  (This 

may  be  A.  ferax.  See  Fischer  (’93),  p.  336.) 

Achlya  intermedia  Bail.  Naturf-Ver.  Konigsb.,  p.  5.  1861. 

Diplanes  saprolegnioides  Leitgeb.  Jahrb.  f.  wiss.  Bot.  7:  374,  pi. 
24.  1869. 

Saprolegnia  semidioica  Petersen.  Bot.  Tidssk.  29:  378.  1909;  also 
Ann.  Myc.  8:  519.  1910. 

The  typical  form  of  this  species  as  understood  by  European  botan¬ 
ists  has  not  been  recognized  in  any  of  our  collections,  and  its  presence 
in  America  is  somewhat  doubtful.  The  form  reported  by  Humphrey 
seems  to  be  the  var.  glomerata,  and  it  does  not  appear  what  form  Atkinson 
had  from  Alabama.  We  include  the  species  as  American  from  the  Michigan 
record  by  Pieters  (Alycologia  7 :  307,  pi.  170,  fig.  2.  1915;  also  listed  in  Ann. 
Mich.  Acad.  Sci.  17:195.  I9I5)  who,  while  he  does  not  give  the  necessary  data 
to  determine  his  form,  does  show  in  his  drawing  an  oogonium  with  at  least 
eight  eggs  which  by  measuring  and  reducing  to  scale  seem  to  be  about  15- 
i8;j.  thick,  a  size  in  accordance  with  the  type  as  understood  by  Fischer. 

Pieters  has  shown  (’15a,  p.  312)  that  in  0.05%  haemoglobin  the  num¬ 
ber  of  oogonia  with  antheridia  is  reduced  to  0-1 7%.  For  other  experiments 


50 


THE  SAPROLEGNIACEAE 


by  Pieters  on  this  species  in  various  media  see  Am.  Jour.  Bot.  2:  529. 
1915.  Pieters  also  writes  us  of  an  interesting  observation  of  his  on 
this  species,  that  in  plates  of  pea  agar  that  had  become  infected  with 
bacteria  the  oogonia  were  very  abundantly  produced  on  the  hyphae 
along  which  the  bacteria  were  thickest,  but  not  along  the  hyphae  where 
the  bacteria  were  few. 

Next  to  Pringsheim ’s,  which  is  ill-defined,  the  most  authentic  de¬ 
scription  of  the  species  may  be  taken  as  that  by  deBary  (’88,  p.  616), 
who  writes  as  follows  (translation) : 

“Main  threads  straight,  tense.  Primary  sporangia  slender,  clavate- 
cylindric.  Antheridial  branches  androgynous,  forming  antheridia  on  all 
the  oogonia,  almost  always  arising  near  and  springing  from  the  same 
stalks  as  the  oogonia  to  which  they  are  attached  or  from  neighboring 
ones.  Oogonia  usually  borne  on  racemosely  arranged,  bent  or  straight 
short  branches  which  are  about  as  long  as  the  diameter  of  the  oogonia; 
the  main  hyphae  from  which  these  spring  ending  in  an  oogonium,  or  a 
sporangium,  or  a  sterile  point.  Oogonia  spherical,  smooth,  with  several 
large  pits  in  the  membrane.  Oospores  from  one  to  over  30,  mostly  5-10 
in  an  oogonium,  centric.  Antheridia  bent-clavate,  with  the  concave 
side  applied  to  the  oogonium.” 

Fischer  gives  the  eggs  as  16 -22\i  thick.  Minden  (’12,  p.  608)  thinks 
that  S.  semidioica  of  Petersen  is  the  same  as  S.  monoica,  and  to  all  appear¬ 
ances  he  is  right.  According  to  Lindstedt  (’72,  p.  64)  Achlya  intermedia 
Bail  (’61)  is  a  synonym  of  Diplanes  saprolegnioides.  For  other  illustrations 
of  S.  monoica  see  Reinke  (’69),  pi.  12;  deBary  (’81),  pi.  5,  figs.  11-19, 
and  pi.  6,  figs.  1-2;  Pringsheim  (’58),  pis.  19  and  20 ;  Ward  (’83),  pi- 
22,  figs. 11- 22;  Rothert  (’88),  pi.  10,  fig.  14;  Massee  (’91),  pi.  5,  figs. 
91-93;  also  Dangeard  and  Claussen  as  cited  below. 

Fertilization  has  been  convincingly  proved  for  this  species  by  Claus¬ 
sen  (’08).  Flis  results  may  be  summarized  as  follows:  Young  oogonia 
are  full  of  protoplasm  and  contain  many  nuclei;  degeneration  of  both 
protoplasm  and  nuclei  takes  place  from  the  center  outward  until  there 
remains  only  a  rather  thin  layer  of  peripheral  protoplasm  containing 
comparatively  few  nuclei ;  these  remaining  nuclei  now  divide  once  my- 
totically  at  the  same  time,  showing  about  10-14  chromosomes;  of  the 
resulting  nuclei  all  degenerate  except  one  for  each  egg.  A  centrosome 
with  radiating  fibers  is  observed  with  the  nucleus  in  this  division  in  the 
oogonium,  and  it  remains  visible  in  the  nucleus  of  the  young  egg.  It  is 
not  to  be  observed  at  time  of  fusion  of  the  egg  and  sperm  nuclei.  The 
antheridia  contain  a  varying  number  of  nuclei  which  divide  simultane¬ 
ously  with  those  of  the  oogonia;  fertilizing  tubes  are  formed  which  are 
simple  or  much  branched.  One  male  nucleus  is  discharged  into  each 
egg  and  soon  reaches  the  egg  nucleus,  the  two  remaining  pressed  to- 


SAPROLEGXIA 


5 1 


gether  for  a  long  time  before  completely  fusing  and  losing  their  identity. 
No  reduction  of  chromosome  number  takes  place  in  the  antheridia  and 
oogonia  before  fertilization;  though  not  observed,  such  reduction  prob¬ 
ably  occurrs  in  the  germinating  egg.  For  other  cytological  data  see  Dan- 
geard  (’90),  p.  in,  pi.  6,  figs.  1-5. 

8.  Saprolegnia  monoica  var.  glomerata  Tiesenhausen.  Arch.  f. 

Hydrobiologie  und  Planktonkunde  7:  277,  hgs.  6-8.  1912. 

Plates  4  and  13 

The  typical  Chapel  Hill  strain  of  this  variety  may  be  described  as 
follows  (No.  7  of  April  3,  1913): 

Growth  moderately  extensive,  the  hyphae  not  very  robust;  sporangia 
abundant,  cylindrical  or  long  club-shaped,  later  ones  more  irregular, 
proliferating  from  within  or  not  rarely  from  one  side  also,  varying  greatly 
in  size,  rarely  so  small  as  to  have  only  a  single  row  of  spores;  spores 
1  o  1 1  p.  in  diameter;  gemmae  abundant  or  few,  often  in  moniliform  chains, 
pear-shaped  or  irregularly  club-shaped,  often  nodulated  or  branched, 
quickly  forming  spores  when  brought  into  fresh  water;  oogonia  abun¬ 
dant,  usually  lateral  on  short  stalks  which  are  mostly  a  quarter  to  equally 
as  long  as  the  diameter  of  the  oogonia,  rarely  intercalary,  occasionally 
terminal  and  then  usually  cylindrical  in  old  sporangia;  wall  colorless, 
moderately  thick,  the  pits  few  or  numerous  in  the  same  culture,  and 
rather  conspicuous,  5.5—791.  in  diameter.  Eggs  centric,  generally  one, 
two,  or  four,  occasionally  six  or  eight,  rarely  20  (or  more?),  diameter 
24-314;  usually  about  25-274.  Antheridial  branches  short,  typically 
clustered  and  contorted,  often  branched,  arising  androgynously  from 
the  main  branches  near  the  oogonia  or  at  times  from  the  oogonial  stalks, 
not  rarely  reaching  also  to  nearby  oogonia  on  other  threads  (diclinous) ; 
antheridia  pear-shaped  or  tuberous,  one  or  more  on  every  oogonium; 
antheridial  tubes  formed. 

The  plant  is  evidently  rare  in  Chapel  Hill,  as  we  have  recognized 
it  with  certainty  only  once — in  the  brook  in  Battle’s  grove  (No.  7  of 
April  3,  1912).  Also  reported  by  Humphrey  from  Cambridge  and 
Amherst,  Massachusetts,  as  S.  monoica  (see  below).  It  is  easily  dis¬ 
tinguished  from  A.  ferax,  which  seems  nearest,  by  the  short,  clustered, 
androgynous  antheridial  branches  with  antheridia  on  every  oogonium. 
The  antheridia  are  usually  several,  sometimes  numerous  and  of  both 
androgynous  and  diclinous  origin,  nearly  always  one  or  more  androg¬ 
ynous  ones  on  an  oogonium  and  very  often  diclinous  ones  also. 

There  are  important  differences  between  this  plant  and  European 
interpretations  of  the  typical  S.  monoica,  these  appearing  in  the  larger 
size  and  fewer  number  of  the  eggs  in  the  American  form  on  the  average. 
Humphrey  refers  to  S.  monoica  a  plant  with  eggs  about  264  on  the 
average,  agreeing  with  ours,  and  he  gives  the  number  as  commonly  not 


52 


THE  SAPROLEGXIACEAE 


above  io,  rarely  numerous”  (see  his  figures  37-39,  pi.  16).  See  under 
S.  monoica  for  note  on  the  Michigan  plant  found  by  Pieters.  There 
seems  no  doubt  that  our  Chapel  Hill  plant  and  Humphrey’s  plant  are 
the  same  as  Tiesenhausen’s  var.  glomerata,  which  he  describes  as  follows 
(translation) : 

“Turf  delicate,  up  to  1  cm.  broad.  The  side  branches  are  thick¬ 
ened,  branched  and  contorted  to  form  small  knots,  some  of  which  are 
sterile  and  mixed  with  similar  ones  bearing  oogonia.  Sporangia  as 
usual,  with  addition  of  conidia-like  sporangia  of  various  shapes,  as  pyri¬ 
form  or  round.  Oogonia  on  principal  and  side  branches,  37-80^.  thick, 
stalks  variously  contorted  and  bent,  often  knee-shaped  or  knotted, 
much  branched,  wall  as  a  rule  without  pits,  seldom  with  several.  Eggs 
22-24;i,  thick;  1-2 1,  mostly  3-6  in  an  oogonium.  Antheridia  always 
present,  springing  from  the  oogonial  stalk  or  main  thread  or  also  from 
nearby  threads.”  Found  in  a  small  lake  near  Zermatt,  Switzerland. 

Continuing  the  discussion  the  author  brings  out  the  fact  that  his 
variety  differs  from  5.  monoica  in  the  peculiar  contorted  clumps  of  side 
branches  and  stalks  and  also  in  the  larger  eggs  (io-22a  in  S.  monoica 
as  he  finds).  Oogonial  initials  that  are  already  provided  with  anther¬ 
idia  may  halt  and  become  sporangia.  It  is  plain  that  this  is  our  form 
of  S.  monoica ,  the  figures  also  agreeing  well.  It  would  appear  from 
Maurizio’s  description  of  his  S.  floccosa  that  it  is  very  near  if  not  the 
same  as  the  above  (see  p.  74). 

Rarely  one  or  more  very  small  eggs  about  half  the  normal  size  are 
found  in  our  plant  mixed  with  the  others,  and  oogonia  have  been  observed 
which  contained  only  such  subnormal  eggs  (fig.  10).  Dwarfed  spor¬ 
angia  with  a  single  row  of  spores  are  met  with,  as  are  also  dictiospor- 
angia.  Thick  clusters  of  short,  distorted  branches  that  seem  to  be 
antheridial  branches  are  not  rarely  seen  in  some  cultures  without  the 
near  presence  of  oogonia.  This  seems  to  be  an  abnormality  induced  by 
the  medium.  In  cases  where  the  cylindrical  oogonia  are  found  inside 
emptied  sporangia  there  may  be  diclinous  antheridia  wrapped  about  the 
sporangium,  and  at  times  one  may  enter  the  sporangium  tip  and  run 
down  inside  to  the  oogonium.  Androgynous  antheridia  are  usually  also 
present  in  such  cases,  running  up  inside  from  below. 

The  following  experiments  were  made  with  single  spore  cultures 
from  No.  7  of  April  3,  1912: 

In  equal  parts  of  5%  maltose  and  .01%  peptone  solution.  Completely  filled  the  petri 
dish  with  very  delicate  threads.  No  gemmae,  sporangia,  or  oogonia  of  good  shape, 
but  a  few  bladdery  initials  were  found  which  later  sprouted  by  one  or  more  tubes  from 
any  point  on  the  surface.  This  experiment  was  twice  repeated  with  the  same  results, 
except  that  there  were  more  initials  formed.  The  stalks  of  these  bodies  were  often 
twisted  and  curved. 


PLATE  13 


PLATE  13 


Saprolegnia  monoica  var.  glomerata 

Fig.  I.  Spores  encysted  within  a  typical  sporangium.  X  167. 

Fig.  2.  Gemmae  in  a  chain.  X  247. 

Fig.  3.  Oogonium  with  gemmae  growing  out  from  beneath  it.  X  247. 

Fig.  4.  Empty  sporangium  containing  a  cylindrical  oogonium  and  an  antheridium.  X  247 

Fig.  5.  Gemmae.  X  247. 

Fig.  6.  Proliferating  sporangia.  X  447. 

Fig.  7.  Sporangium  growing  from  beneath  an  old  one  as  in  Achlya.  X  247. 

Fig.  8.  Apical  oogonium  with  conspicuous  pits  and  with  a  thick-walled  outgrowth  from  be 
low.  X  447- 

Fig.  9.  A  typical  oogonium  with  antheridia.  X  447. 

Fig.  10.  Oogonium  with  abnormally  small  eggs.  X  447. 

Fig.  11.  Oogonium  with  androgynous  and  diclinous  antheridia.  X  247. 


PLATE  ]3 


PLATE  14 


ACHLYA  RACEMOSA  [ABOVE].  X  6. 
SAPROLEGNIA  DICLINA  [BELOW].  MAGNIFIED 


1 


SAPROLEGNIA 


53 


In  pea  broth,  February  28,  1913.  Extensive  growth.  Large  number  of  gemmae.  No 
sporangia  or  oogonia.  The  culture  remained  healthy  and  alive  in  this  broth  for  about 
two  months. 

In  corn  meal  agar.  Grew  vigorously  and  formed  an  immense  number  of  oogonia.  Most 
were  normal  with  good  eggs  and  with  antheridia.  Many  were  inflated  and  no  eggs 
formed.  Many  gemmae  were  also  present.  This  is  the  only  Saprolegnia  except 
S.  ferax  that  forms  eggs  in  this  medium,  and  the  oogonia  here  are  not  so  perfect  as  in 
that  species.  Culture  repeated  twice  with  same  results. 

In  p2  corn  meal  T  A  egg  yolk  agar,  March  4,  1913.  Vigorous  growth  covering  dish.  An 
immense  number  of  good  oogonia  on  rather  longer  stalks  than  usual.  The  stalks  bear 
at  a  little  distance  below  the  oogonium  (about  the  middle)  a  forest  of  short  lateral 
threads,  often  branched,  which  may  or  may  not  reach  the  oogonium.  When  near 
enough  they  will  also  apply  themselves  to  other  oogonia.  This,  so  far,  is  the  medium 
that  produces  the  most  striking  characters  of  this  species.  No  gemmae. 

On  whole  egg  agar,  March  13,  1913.  Strong  growth.  A  good  many  sporangia.  An  im¬ 
mense  number  of  oogonia  with  average  of  4—6  eggs.  Antheridia  on  every  oogonium, 
generally  several ;  almost  always  some  androgynous  ones,  and  perhaps  2%  of  the  oogonia 
with  diclinous  ones  in  addition.  Many  short  branches  here  and  there  like  abortive 
antheridia. 

On  a  bit  of  whole  egg  agar  in  distilled  water.  Oogonia  nearly  always  on  short  lateral  branches 
(95 %  or  more),  occasionally  terminating  main  hyphae  (5%  or  less).  Eggs  generally 
4,  rarely  6. 

The  following  tests  (single  spore  culture  of  No.  7  of  April  3,  1912)  were 
made  to  find  the  best  way  to  preserve  the  life  of  cultures: 

(a)  Two  cultures  were  made  January  15,  1912,  in  sterile  bottles  containing  pea  broth 
(50  peas  boiled  an  hour  or  more  in  500  cc.  water).  Growth  was  good,  and  when  ex¬ 
amined  after  a  month  showed  results  as  follows:  In  pea  broth  alone,  there  was  only 
vegetative  growth  and  all  was  dead;  on  ant  larva  in  pea  broth  there  were  formed  plenty 
of  oogonia  and  perfect  eggs  that  were  still  alive,  other  parts  dead,  (b)  In  May,  1913, 
a  culture  was  put  in  a  vial  of  water  by  cutting  out  a  piece  of  corn  meal  agar  on  which 
it  was  growing.  An  ant  larva  was  also  dropped  in  at  the  same  time.  The  vial  was 
closed  with  a  plug  of  cotton  and  left  in  a  dark  place  in  the  laboratory  over  summer. 
A  test  for  life  was  made  in  December,  1913,  by  dropping  a  mushroom  grub  in  the  vial, 
and  renewed  growth  resulted.  The  old  eggs  were  alive  (as  shown  by  their  normal 
structure)  both  in  the  agar  and  on  the  ant  that  was  put  in  at  the  same  time  with  the 
agar,  but  none  had  sprouted,  (c)  Culture  was  put  in  vial  on  corn  meal  agar  March  18, 
1913,  and  found  to  be  dead  December  1,  1913.  (d)  A  culture  on  an  insect  was  put  in  an 

aquarium  jar  with  algae  on  March  3,  1913.  Test  for  life  was  made  in  September,  1917, 
by  dropping  in  mushroom  grubs  but  no  growth  appeared. 

9.  Saprolegnia  monoica  var.  vexans  Pieters.  Bot.  Gaz.  60 :  489.  1915. 

We  have  not  found  this,  and  the  following  is  taken  from  the  original 
description  by  Pieters: 

“This  was  secured  from  algal  material  collected  at  Sukey  Lake, 
near  Ann  Arbor,  Michigan.  The  vegetative  growth,  sporangial  char¬ 
acters,  and  the  formation  and  shape  of  gemmae  do  not  differ  in  any 
particular  from  those  present  in  S.  monoica,  S.  ferax,  or  any  other  species 


54 


THE  SAPROLEGNIACEAE 


of  that  group  except  5.  mixta,  which  has  weaker  hyphae.  The  material 
was  cultivated  for  nearly  a  year  and  a  half  on  flies,  in  agar,  and  by  trans¬ 
fer  from  a  strong  culture  medium  such  as  pea  decoction  or  peptone, 
into  haemoglobin,  leucin,  peptone,  or  other  solution.  During  all  this 
time  no  oogonia  were  produced.  Toward  the  end  of  this  time  a 
series  of  tests  was  made  with  several  cultures  by  transferring  vigorous 
mycelium  to  leucin  to  which  various  sugars  and  salts  had  been  added. 
Among  other  combinations  there  was  used  leucin  5^5+ levulose  5^, 
and  in  this  a  mycelium  out  of  pea  extract  produced  an  abundance  of 
oogonia.  When  these  were  examined  they  proved  to  be  indistinguish¬ 
able  from  the  oogonia  and  antheridia  of  S.  monoica  Pringsh.  Rarely  an 
oogonium  was  found  on  which  there  was  no  antheridium,  but  in  some 
solutions  this  may  also  be  the  case  with  S.  monoica. 

“The  fact  that  cultures  of  S.  monoica  were  going  on  at  the  same 
time  suggested  the  possibility  of  contamination.  Check  cultures  were 
made,  therefore,  by  taking  mycelium  from  the  dish  in  which  the  oogonia 
were  formed  and  growing  this  on  fly.  Had  the  mycelium  producing 
oogonia  been  that  of  S.  monoica  (No.  79c  of  my  series),  plenty  of  oogonia 
would  have  been  produced.  In  fact,  no  oogonia  were  formed  on  the 
fly  culture,  but  a  fresh  culture  from  this  fly  through  pea  decoction  into 
leucin  and  levulose  again  produced  oogonia  as  before. 

“We  seem  to  have  here,  therefore,  the  remarkable  case  of  a  variety 
of  S.  monoica  having  lost  sexuality,  but  recovering  it  under  stimulus 
of  this  special  combination,  leucin  and  levulose  in  concentration  each. 

“The  gemmae  of  this  form  are  perhaps  a  little  more  varied  in  shape 
than  is  the  case  with  the  species,  but  the  shape  of  these  organs  is  so 
variable  in  most  species  that  they  are  of  no  value  for  systematic  pur¬ 
poses. 

“Had  time  permitted,  it  would  have  been  interesting  to  cultivate 
this  form  for  many  generations  in  leucin-levulose  solutions  to  determine 
whether  the  vigorous  production  of  oogonia  which  characterizes  such 
forms  of  S.  monoica  as  my  79c  would  be  regained  by  this  variety. 

“The  forms  described  in  this  paper  are  remarkable  examples  of  the 
intimate  dependence  of  the  members  of  this  group  on  external  condi¬ 
tions.” 

10.  Saprolegnia  litoralis  n.  sp. 

Plates  15  and  16 

Growth  about  as  in  Saprolegnia  ferax ,  more  vigorous,  extensive 
and  irregular  than  in  Saprolegnia  delica,  the  hyphae  reaching  a  length  of 
1-1.5  cm.  on  a  mushroom  grub.  Sporangia  not  abundant,  far  less  so 
than  in  Saprolegnia  diclina,  early  ones  nearly  cylindrical,  or  more  often 


PLATE  15 


PLATE  15 

Saprolegnia  litoralis 

Fig.  I.  An  oogonium  with  an  apical  papilla.  X  278. 

Fig.  2.  Gemma  with  3  papillae  which  has  emptied.  X  278. 

Fig.  3.  Sporangium  with  long  papilla.  X  278. 

Fig.  4.  Proliferating  sporangia.  X  278. 

Figs.  5  and  6.  Gemmae.  X  278. 

Fig.  7.  Gemma  with  2  papillae  which  have  formed  spores  and  emptied.  X  278. 
Fig.  8.  Sporangia  and  gemmae.  X  278. 

Fig.  9.  Empty  gemmae  with  two  papillae  from  the  same  spot.  X  278. 

Fig.  10.  Gemmae.  X  278. 


PLATE  15 


SAPROLEGNIA  LITORALIS 


PLATE  16 


PLATE  16 

Saprolegnia  litoralis 

Fig.  I.  Oogonium  with  mature  eggs.  X  503. 

Fig.  2.  Young  oogonium.  X  503. 

Fig.  3.  Young  oogonia  with  typical  antheridia.  X  503. 

Fig.  4.  Oogonium  with  antheridial  tubes  after  the  antheridia  have  emptied. 
Fig.  5.  Intercalary  oogonium.  X  278. 

Fig.  6.  A  short-stalked  oogonium.  X  278. 

Fig.  7.  Apical  oogonium  with  unemptied  antheridia.  X  503- 


x  503- 


PLATE  1G 


m  • . 


SAPROLEGNIA  LITORALIS 


SAPROLEGNIA 


55 


irregular  in  diameter,  usually  curved,  repeatedly  proliferating,  later  ones 
more  irregular  and  often  pointed;  spores  10-12^  in  diameter.  Gemmae 
very  abundant,  spherical,  pyriform,  clavate,  etc.,  often  in  chains,  the 
terminal  one  very  often  with  an  elongated  papilla.  Oogonia  plentiful 
as  a  rule,  about  as  much  so  as  in  Saprolegnia  ferax,  but  at  times  not 
found  on  grubs  in  distilled  water  (more  scattered  than  in  Saprolegnia 
delica  and  Saprolegnia  anisospora ),  about  35-804  thick,  the  larger  num¬ 
ber  terminal  on  main  hyphae,  others  (usually  appearing  later)  on  short 
lateral  branches;  shape  spherical,  or  if  borne  on  the  ends  of  main  threads 
usually  oval,  the  latter  frequently  with  a  slender,  more  or  less  lengthy 
terminal  extension,  which  when  short  may  be  included  in  the  cavity  of 
the  oogonium,  but  which  is  often  extended  into  a  thread  2.8-34  thick, 
thus  making  the  oogonium  intercalary;  furnished  with  rather  few,  very 
conspicuous  and  usually  large  pits,  up  to  114  across.  Eggs  centric, 
large  and  dark,  1-20,  mostly  2-6  in  an  oogonium,  their  diameter  20-404, 
most  about  30-334,  often  elliptic  from  pressure.  Antheridia  on  every 
oogonium  (one  to  several),  androgynous  on  short  branches  which  usually 
arise  very  near  the  oogonium,  frequently,  when  the  oogonium  is  on 
a  short  stalk,  arising  from  immediately  below  it.  In  addition  to  the 
androgynous  antheridia  a  few  diclinous  ones  may  arise  rarely  from  other 
nearby  threads. 

We  have  not  found  this  in  Chapel  Hill,  our  only  collections  having 
been  taken  by  us  in  fresh  water  with  algae  in  a  roadside  ditch  near  South- 
port,  N.  C.  (No.  3  of  April  6,  1918),  and  in  a  ditch  at  the  golf  links,  Wil¬ 
mington,  N.  C.,  Dec.  27,  1922. 

There  seems  little  doubt  that  this  is  near  the  European  Saprolegnia 
paradoxa  of  Maurizio*  (see  p.  75)  which  agrees  in  the  characteristic 
antheridial  branches  and  in  the  apical  extension  on  some  of  the  oogonia. 
We  would  refer  our  plant  to  this  species  except  for  the  much  smaller  eggs 
and  frequent  presence  of  an  ingrowing  process  from  below  in  the  oogonia 
of  the  latter. 

The  present  species  is  obviously  near  Saprolegnia  monoica ,  but  is 
clearly  distinct  in  the  much  larger  eggs,  the  absence  of  an  ingrowing 
tube  from  the  oogonial  wall  below,  in  the  presence  of  a  slender  exten¬ 
sion  on  the  tips  of  many  of  the  oogonia  and  gemmae,  and  in  the  typically 
more  abundant  and  more  branched  antheridial  branches.  These  latter, 
when  the  oogonium  is  apical  on  a  main  thread,  may  be  so  abundant  and 
branched  as  to  give  the  effect  of  a  basket  holding  the  oogonium.  It  is 
possible  that  this  is  the  plant  Minden  found  and  describes  as  S.  spiralis 
Cornu  and  thinks  is  the  same  as  S.  retorta  Horn.  If  his  plant  is  indeed 
the  same  as  ours  it  is  not  S.  retorta,  which  is  easily  different,  nor  does 
our  plant  correspond  to  Cornu  s  imperfect  description  of  S.  spiralis. 

*Not  of  Petersen,  which  was  published  about  ten  years  later:  see  under  Aplanes 
Treleaseanus  (p.  79)  • 


56 


THE  SAPROLEGNIACEAE 


The  following  cultures  were  made  from  No.  3  of  April  6,  1918: 

On  corn  meal  agar.  Growth  vigorous,  covering  agar  plate;  sporangia  rare;  gemmae  pres¬ 
ent  in  chains;  fair  number  of  oogonia  produced;  antheridia  on  every  oogonium. 

On  boiled  corn  grain.  Growth  very  vigorous;  sporangia  as  normally  produced;  many 
gemmae;  a  good  many  oogonia  of  normal  shape  and  appearance.  This  culture  was 
repeated  and  it  was  observed  that  the  gemmae  became  sporangia,  emptying  their 
spores  by  a  quite  lengthened  papilla  upon  change  of  conditions,  such  as  pouring  on 
fresh  water  or  transference  from  ice  box  to  open. 

Many  other  cultures  were  made,  of  course,  on  insects,  grubs,  flies, 
etc.,  with  results  considered  normal  as  described. 

11.  Saprolegnia  megasperma  n.  sp. 

Plate  17 

Mycelium  on  grubs  and  vegetable  media  about  as  vigorous  as  in 
Saprolegnia  ferax  or  S.  litoralis;  threads  on  mushroom  grubs  or  termites, 
9-35P.  thick,  most  about  I5~20p.  thick,  reaching  a  length  of  0.5 -0.7  cm.; 
threads  straight  to  wavy,  usually  wavy  on  termites.  Sporangia  abundant 
on  grubs,  termites,  and  vegetable  media,  apical,  15-45  X  100-400^, 
variable  in  shape :  the  first  ones  usually  long  and  distinctly  swollen  at  the  dis¬ 
tal  end,  later  ones  usually  smaller  and  more  or  less  irregular  in  outline ;  emp¬ 
tying  normally  for  the  genus;  renewed  by  internal  proliferation  or  rarely  by 
cymose  branching  as  in  Pythiopsis  or  A  clilya.  Not  rarely  in  cultures  slightly 
infected  with  bacteria  the  sporangia  may  break  away  from  the  threads 
as  in  Dictyuchus,  such  sporangia  emptying  normally  after  a  long  or  short 
rest.  Spores diplanetic,  biciliate,  1  ip.  thick  when  encysted.  Gemmae  abun¬ 
dant,  round  to  oval  or  very  irregular,  emptying  upon  the  addition  of 
fresh  water  by  one  or  more  long  papillae.  Oogonia  produced  in  fair 
abundance,  inversely  in  proportion  to  the  number  of  sporangia  and 
gemmae,  40-ioop.  thick,  wall  smooth  (rarely  with  a  papilla),  not  thick, 
without  pits  or  rarely  with  a  few  small  ones;  usually  borne  on  short 
racemose  branches  which  in  length  are  as  a  rule  less  than  the  diameter 
of  the  oogonia;  not  rarely  borne  singly  or  in  clusters  of  several  on  the 
ends  of  main  threads  in  cultures  in  which  sporangia  are  sparingly  pro¬ 
duced.  Eggs  1-10,  single  in  over  50%  of  the  oogonia  in  most  cultures 
(not  rarely  running  considerably  above  or  below  this  per  cent) ;  30- 
52  p.  thick,  usually  about  381J.  thick;  subcentric  (one  row  of  oil  droplets 
on  one  side,  two  on  the  other),  not  filling  the  oogonia.  Antheridia 
present  on  all  oogonia,  applied  by  their  ends,  seldom  by  their  sides; 
antheridial  walls  thick,  easily  visible  even  in  old  cultures;  antheridial 
branches  usually  of  androgynous  origin  but  quite  often  diclinous,  usually 
simple  and  unbranched;  antheridial  tubes  developed  and  easily  visible. 

Found  near  Wilmington,  N.  C.,  on  December  30,  1921,  in  water, 
trash  and  a  little  green  algae  collected  from  a  branch  by  the  old  Atlantic 
Coast  Line  Railroad  bed. 

In  its  general  habit  the  above  species  might  be  confused  on  hasty 
study  with  S.  litoralis,  which  also  was  found  near  Wilmington.  But 


PLATE  17 


PLATE  17 

Saprolegnia  megasperma  n.  sp. 

Fig.  1-2.  Typical  sporangia.  X  167. 

Fig.  3.  Spores  stained,  showing  cilia.  X  900. 

Fig.  4.  Sporangia,  one  proliferating  internally.  X  167. 

Fig.  5.  Sporangia  showing  internal  proliferation.  X  167. 

Fig.  6.  Gemmae  which  have  become  sporangia  and  emptied.  X  167. 

Fig.  7.  Typical  forms  and  position  of  gemmae,  one  from  which  the  spores  failed  to 

discharge  completely.  X  167. 

Fig.  8.  Oogonium  with  a  single  egg  and  an  apiculus.  X  247. 

Fig.  9-1 1.  Stages  of  sprouting  gemmae.  Each  gemmae  shows  three  pits  from  which  sprouts 
are  appearin  '  in  two  cases.  X  247 

Fig.  12.  A  gemma  breaking  away  from  the  hvpha  as  in  Dictyuchns.  X  167. 

Fig.  13.  Oogonium  with  a  single  ripe  egg,  and  two  diclinous  antheridia.  X  500. 

Fig.  14.  Oogonium  with  a  single  egg  and  a  diclinous  antheridium  showing  an  antheridial 

tube.  X  500. 

Fig.  15.  Oogonium  with  androgynous  antheridia.  X  447. 

Fig.  16.  Habit  sketch  showing  oogonia,  antheridia  and  gemmae.  X  108. 

Fig.  17.  Habit  sketch  showing  a  sporangium  and  several  gemmae,  one  of  which  has 
developed  an  abortive  antheridium.  X  167. 


PLATE  17 


SAPROLEGNIA  MEGASPERMA. 


SAPROLEGNIA 


57 


the  former  is  obviously  distinct  from  S.  litoralis  in  the  smaller  number 
and  larger  size  of  the  eggs,  in  the  simple,  unbranched  antheridial  stalks, 
in  the  fewer  antheridia,  in  the  absence  of  intercalary  oogonia,  in 
the  greater  abundance  of  sporangia,  and  in  the  extremely  distorted 
gemmae. 

The  present  species  can  be  readily  recognized  after  the  formation 
of  eggs  by  the  large  number  of  oogonia  with  single  eggs  (usually  over 
50%);  by  the  simple,  unbranched  antheridial  stalks,  and  the  antheridia 
which  apply  themselves  to  the  oogonia  by  their  ends  instead  of  by  their 
sides.  The  above  characters  will  serve  in  identifying  the  plant,  but 
the  number  of  oogonia  and  even  the  number  of  oogonia  with  single  eggs 
varies  considerably  under  different  conditions  of  culture.  These  facts 
will  be  brought  out  in  the  following  general  summary  of  results  of  ex¬ 
periments. 

It  has  been  found  that  the  number  of  oogonia  produced  varies  inversely 
with  the  number  of  sporangia  produced.  When  cultures  were  made  in 
the  ordinary  way  and  left  to  grow  for  about  five  days,  only  a  fairly  good 
number  of  sporangia  were  formed  while  a  very  large  number  of  oogonia 
were  produced,  oogonia  often  being  borne  in  clusters  at  the  ends  of 
hyphae  in  addition  to  the  usual  number  of  racemose  ones;  on  the  other 
hand  when  fresh  water  was  added  to  the  cultures  sporangia  were  formed 
on  the  ends  of  practically  all  the  hyphae,  the  oogonia  present  being  rac- 
emosely  borne.  On  grubs  and  termites  the  oogonial  walls  are  unpitted, 
but  on  bits  of  corn  grain  the  walls  of  about  10  to  20%  of  the  oogonia 
show  a  few  conspicuous  pits. 

Quite  often,  especially  when  bacteria  were  present,  clusters  of  gemmae 
were  formed  on  the  ends  of  the  threads,  the  gemmae  resting  until  the 
addition  of  fresh  water.  When  the  plant  is  cultivated  on  termites  the 
threads  are  spirally  twisted  and  the  oogonia  are  mostly  borne  in  elaborate 
clusters  on  the  ends  of  threads,  about  75%  of  the  oogonia  containing 
single  eggs,  the  number  in  the  rest  of  the  oogonia  being  two,  three  or 
four  or  very  rarely  more.  On  mushroom  grubs  the  threads  are  usually 
nearly  straight  and  clusters  of  oogonia  are  rare,  about  50%  of  the  oogonia 
containing  single  eggs. 

12.  Saprolegnia  parasitica  n.  sp. 

Plate  18 

.  Growth  rather  delicate  on  insects  and  other  usual  media,  moder¬ 
ately  dense,  not  long,  rarely  reaching  1  cm.  on  a  mushroom  grub.  Gem¬ 
mae  abundant,  size  and  shape  very  variable;  often  in  chains,  mostly 
terminating  hyphae,  but  sometimes  intercalary.  Sporangia  variable, 
but  usually  bent  and  irregular,  at  times  up  to  0.7  mm.  long,  very  often 


58 


THE  SAPROLEGXIACEAE 


proliferating  from  the  side  below  as  in  Achlya;  when  growing  through 
others  sometimes  discharging  spores  through  the  side  wall  of  the  old 
sporangium;  spores  9-1 1.5^  thick,  in  our  form  swimming  in  two  stages  as 
usual  in  the  genus  (not  swimming  in  Huxley’s  form — see  below).  Sexual 
reproduction  not  observed  so  far  in  our  form  and  very  rarely  observed 
by  others  (Huxley).  Received  by  us  from  the  fish  hatchery  at  Wythe- 
ville,  Va.,  and  from  the  aquarium  of  the  U.  S.  Fish  Commission  in  Wash¬ 
ington,  in  each  case  growing  as  a  parasite  on  fish. 

There  is  every  reason  to  think  that  this  is  the  same  as  the  sterile 
Saprolegnia  that  has  been  reported  so  often  as  causing  (or  appearing 
with)  a  well-known  diseased  condition  of  fish.  The  disease  is  apt  to 
appear  at  any  time  on  young  fingerlings  in  fish  hatcheries  or  on  the  eggs 
and  may  at  times  be  a  serious  pest.  It  is  also  apt  to  appear  now  and 
then  on  gold  fish  and  in  fish  pools  and  aquaria  and  sometimes  causes 
(or  accompanies)  epidemics  of  disease  which  result  in  great  mortality 
of  salmon,  trout,  etc.,  in  the  free  waters  of  rivers  and  lakes. 

That  the  species  is  almost  or  quite  without  oogonial  reproduction 
is  evidenced  by  the  fact  that  only  very  rarely  have  oogonia  been  reported 
(and  then  without  proof  that  they  belonged  to  the  parasite),  notwithstand¬ 
ing  the  fact  that  this  species  has  been  more  studied  perhaps  than  any 
other  of  the  family.  The  plant  was  for  a  long  time  carelessly  spoken  of 
as  S.  ferax,  but  in  the  few  cases  of  sexual  reproduction  observed  there 
is  a  close  similarity  to  that  of  X.  monoica.  This  resemblance  is  so  close 
in  fact  that  Huxley,  who  was  the  first  to  report  the  oogonia  (Quart.  Jour. 
Mic.  Sci.  22:  31 1.  1882),  considered  it  5.  monoica  (S.  ferax  var.  monoica, 
he  called  it).  Nevertheless  we  do  not  think  we  are  justified  in  consider¬ 
ing  the  (at  least  practically)  sterile  parasite  in  question  the  same  as 
the  well-known  and  abundantly  fruitful  saprophytic  N.  monoica,  even 
though  they  are  much  alike  in  other  respects.  The  tendency  to 
proliferate  from  the  side  below,  as  in  Achlya,  is  from  our  observations 
even  more  strong  in  this  species  than  in  S.  monoica.  Huxley  reports 
that  in  his  plant  the  spores  did  not  swim  on  emerging  but  floated  pas¬ 
sively.  Our  plant  does  not  show  this  character  (if  indeed  it  is  a  per¬ 
manent  character  in  any  form,  which  is  more  than  doubtful),  the  spores 
swimming  as  usual  in  the  genus.  It  is  interesting  to  note  here  the 
similar  suppression  of  a  swimming  stage  in  Achlya  aplanes  which  is  other¬ 
wise  very  like  A.  prolifera. 

For  comparison  it  will  be  of  interest  to  refer  to  Rothert’s  remarks 
on  a  Saprolegnia  found  by  him  on  fish  eggs  (called  S.  sp.  I)  and  probably 
the  same  as  this.  He  says  (1888,  p.  295)  that  although  the  plant  was  quite 
free  from  parasites  and  was  cultivated  for  a  half  year  in  various  conditions 
he  was  not  able  to  induce  the  formation  of  oogonia.  That  so  far  as 


PLATE  18 


PLATE  18 

Saprolegnia  parasitica 

Figs,  i,  2,  3  and  4.  Various  forms  of  sporangia.  X  447. 

Figs.  5.  6.  7,  and  8.  Gemmae.  X  447. 

Fig.  9.  Spores  in  first  swimming  stage.  X  720. 

Figs.  10,  11,  and  12.  Various  forms  of  sporangia  showing  proliferation. 


X  447- 


PLATE  18 


■ 


SAPROLEGN I A  PARASITICA. 


SAPROLEGNIA 


59 


seen  it  was  so  like  S.  monoica  that  it  was  possibly  identical  with  it;  but 
it  might  also  be  a  distinct  form  quite  without  oogonia,  somewhat  like 
(in  this  respect)  Leptomitus  lacteus.  Hine’s  (’78)  figures  and  descrip¬ 
tion  indicate  the  present  species  (pis.  4-5),  particularly  in  the  prolifera¬ 
tion  of  sporangia  at  times  by  lateral  growth  from  below,  as  in  Achlya 
(p.  95).  He  records  the  natural  infection  of  uninjured  tritons  (Mino- 
branchus )  in  an  aquarium  at  Cornell  University  and  also  experimental 
infections  of  injured  animals  which  died  in  about  three  or  four  days. 
Dictiosporangia  were  also  observed;  but  no  sexual  reproduction.  As 
to  remedies  Hine  notes  the  curing  by  Mr.  Gage  of  an  eel  by  sponging 
it  with  a  ten  per  cent  solution  of  carbolic  acid,  and  of  Minobranchus 
by  sponging  with  camphorated  water.  He  also  quotes  from  Rev.  M.  J. 
Berkeley,  who  says  in  his  Treasury  of  Botany  that  carbonate  of  soda, 
and  probably  also  bisulphate  of  potash,  will  prevent  the  growth  of  these 
parasites. 

The  sterile  species  described  by  Lindstedt  in  his  Synopsis  (p.  48) 
may  possibly  be  this,  but  is  more  probably  a  very  sterile  strain  of  S. 
diclina,  as  he  obtained  it  on  flies  from  water  in  which  had  grown  Chara, 
and  the  drawings  look  more  like  the  latter  species. 

Radais  (1898)  found  a  sterile  Saprolegnia  in  a  conduit  and  referred  it 
with  some  doubt  to  S.  ferax,  which  it  could  hardly  be. 

Tempere  (1904)  calls  a  parasite  on  fish  that  he  found  S.  ferax,  al¬ 
though  oogonia  were  not  observed.  It  was  probably  S.  parasitica. 

Hardy  ( 1 9 1 1 )  found  a  sterile  Saprolegnia  infecting  several  species 
of  young  trout  and  associated  with  the  alga  Myxonema,  the  latter  with 
branched  filaments  about  1  cm.  long  and,  apparently,  more  conspicuous 
than  the  fungus.  The  fungus  was  always  present  with  the  alga,  but 
itself  occurred  alone  at  times.  Hardy  had  previously  noted  this  alga  on 
goldfish  and  incidentally  mentioned  the  presence  of  a  fungus  (1907), 
and  Minakata  had  found  this  alga  on  fish  in  Japan,  but  did  not  men¬ 
tion  a  fungus  associate  (Nature  79:  99.  1908). 

Miss  Collins  (1920)  describes  considerable  variations  in  behavior  of 
the  sporangia  and  spores  in  a  sterile  species  found  by  her  in  South  Aus¬ 
tralia.  It  may  be  the  same  as  ours. 

Huxley  (1882)  has  shown  that  the  Saprolegnia  he  studied  could 
advance  into  sound  tissue  from  infected  areas  and  was  thus  capable 
of  being  a  parasite.  It  is  of  course  not  an  obligate  parasite,  and  Hardy 
(1.  c.)  suggests  that  its  attacks  on  fish  may  be  prepared  for  by  parasitic 
bacteria  such  as  Bacillus  salmonis  pestis  or  B.  piscicidus  bipolaris. 

To  test  for  length  of  life  a  pure  culture  was  put  in  a  jar  of  distilled  water  in  March, 
I917.  Grubs  placed  in  contact  with  this  culture  several  times  between  Sept.  14  and  25, 
1917,  failed  to  show  growth. 


6o 


THE  SAPROLEGNIACEAE 


13.  Saprolegnia  hypogyna  Pringsheim.  Jahrb.  f.  wiss.  Bot.  9:  191,  pi. 
18,  tigs.  5,  9,  10.  1873. 

Saprolegnia  intermedia  Maurizio.  Jahrb.  f.  wiss.  Bot.  29:  97,  pi.  2, 
figs.  37-5 1  a.  1896. 

First  described  briefly  by  Pringsheim  as  a  variety  of  S.  ferax  (but 
referred  to  as  S.  hypogyna  in  the  description  of  the  figures),  this  plant 
was  later  recognized  as  a  species  by  deBary  (Bot.  Zeit.  46:  615.  1888). 
It  is  defined  by  Pringsheim  and  deBary  as  having  no  antheridial 
branches,  but  with  an  antheridial  cell  cut  off,  usually  just  below  the 
oogonium,  from  which  an  antheridial  tube  pushes  up  through  the  wall  in 
most  cases.  As  even  the  more  typical  Michigan  form  departs  in  certain 
respects  from  the  European,  we  add  below  deBary ’s  description  for  com¬ 
parison  : 

'‘Threads  delicate,  strict;  primary  sporangia  repeatedly  proliferating 
from  within.  Oogonia  terminal  and  then  mostly  round  or  pear-shaped, 
or  intercalary  and  then  broadly  barrel-shaped,  not  rarely  two  or  more 
in  a  row;  wall  smooth,  moderately  thick,  with  not  very  numerous  large 
pits.  Egg  usually  about  5-10  (1-40),  centric  as  in  A.  monoica.  Anther¬ 
idial  branches  absent;  antheridia  usually  present  in  the  form  of  a  cylindrical 
or  clavate-cylindrical  cell,  which  is  cut  off  just  below  the  oogonium; an¬ 
theridial  tubes  usually  entering  the  oogonia  through  the  basal  wall,  often 
branched  and  not  rarely  absent.  Intercalary  oogonia  when  single  fre¬ 
quently  have  an  antheridium  cut  off  at  each  end  with  antheridial  tubes 
present  or  absent.  A  small  proportion  of  the  oogonia  remain  without 
antheridia  even  to  full  maturity  of  the  eggs.” 

A  form  of  this  species  approaching  the  typical  has  been  found  in 
America  heretofore  only  by  Kauffman  in  Michigan  (Ann.  Bot.  22:  361, 
pi.  23.  1908.  Also  noted  in  Ann.  Rep.  Mich.  Acad.  Sci.  8:  27.  1905). 
He  does  not  describe  in  detail  the  normal  appearance  of  his  plant  on 
insects  in  pure  water,  but  as  he  does  not  mention  the  absence  of  the 
suboogonial  cell  in  such  conditions  it  is  to  be  presumed  that  it  is  regu¬ 
larly  present.  In  a  set  of  experiments  with  haemoglobin  or  peptone 
with  or  without  the  addition  of  various  salts  Kauffman  found  that  in 
case  oogonia  were  produced  the  antheridial  cell  was  always  present  in 
most  of  the  media,  and  partly  absent  in  a  few.  Side  branches  from 
the  antheridial  cell  were  often  present,  and  attached  themselves  to  the 
oogonium  above.  In  K3P04  and  to  a  less  extent  in  KNOs  and  Na2HP04 
the  normal  behavior  could  be  so  modified  that  there  were  formed  numer¬ 
ous  antheridial  branches,  mostly  of  diclinous  origin,  much  as  in  A.  mixta 
and  A.  diclina.  Several  of  Kauffman’s  drawings  (figs.  5,  6,  7,  14,  15  and 
16)  show  androgynous  antheridial  branches  running  up  around  the 
oogonium  from  immediately  below  it,  as  in  var.  Ill  of  Maurizio  (see 
below).  These  two  forms,  therefore,  approach  nearest  to  A  planes  Treleas- 


SAPROLEGNIA 


6r 


eanus,  but  differ  sharply  in  the  presence  of  an  abstricted  hypogynal  cell. 
They  may  be  considered  as  connecting  links  between  A.  Treleaseanus 
and  the  typical  A.  liypogyna.  That  S.  hypogyna  is  very  variable  is  shown, 
not  only  in  Kauffman’s  results,  but  also  by  the  fact  that  Maurizio  has 
described  six  forms,  or  varieties,  and  one  so-called  species  (S.  intermedia), 
which  should  be  reduced  to  a  form,  or  variety,  and  is  so  reduced  by 
Minden.  For  other  illustrations  see  Minden  (’12),  fig.  if  on  p.  520; 
Tiesenhausen  (’12),  figs.  2  and  3;  and  Maurizio  as  cited  below. 

It  is  certain  that  in  S.  hypogyna  and  its  forms  the  upgrowths  into 
the  oogonia  are  in  most  cases  at  least  quite  functionless  as  antheridial 
tubes,  and  are  of  no  more  significance  than  in  many  other  species,  e.  g., 
in  the  Ferax  group,  where  something  of  the  kind  is  often  seen.  In  such 
forms,  however,  as  5.  intermedia  and  Form  V,  where  the  upgrowths 
have  thin  walls  and  dense  protoplasmic  contents,  it  is  still  to  be  shown  that 
they  are  without  function.  For  views  on  this  point  in  practical  agree¬ 
ment  with  the  above  see  Maurizio  (Flora  79:  149.  1894)  and  Kauffman 
(Ann.  Bot.  22:  382.  1908).  The  species  is  reported  from  Lapland  by 
Gaumann  (1918)  who  gives  the  eggs  as  1 7-2010.  thick. 

For  the  use  of  students  it  is  desirable  to  give  a  more  or  less  abbrevi¬ 
ated  description  of  the  seven  varieties  (exclusive  of  Kauffman’s  form) 
as  understood  by  Maurizio.  Five  of  these  (I-V  below)  were  first  de¬ 
scribed  as  varieties  in  Flora  (79:  109,  pi.  4-5.  1894).*  Next  was 

published  S.  intermedia  (Jahrb.  f.  wiss.  Bot.  29:  97.  1896);  and  then 
var.  Coregoni  (Mitt.  d.  Deutsch.  Fischerei-Vereins  7:55.  1899).  We  think 
it  best,  with  our  present  knowledge  (or  rather  lack  of  it)  to  consider 
all  these  variants  as  forms,  giving  them  consecutive  numbers  up  to 
8,  thus: 


Form  1 — Var.  I  of  Maurizio  (pi.  4-5,  figs.  5-12). 

Form  2 — Var.  II  “  “  (pi.  4-5,  figs.  13-16). 

Form  3 — Var.  Ill  “  “  (pi.  4-5,  figs.  I7~20a). 

Form  4 — Var.  IV  “  “  (pi.  4-5.  figs.  21-23). 

Form  5 — Var.  V  “  “  (pi.  4~5>  figs-  24-27). 

Form  6 — S.  intermedia  Maurizio. 

Form  7 — Var.  Coregoni  Maurizio. 

Form  8 — Kauffman’s  form  from  Michigan. 


In  Ivrypt.  FI.  Mark  B.  (5:  528.  1912)  Minden  gives  a  key  to  Mau- 
rizio’s  first  five  varieties  (he  has  overlooked  the  var.  Coregoni)  which  is 
copied  below.  On  account  of  the  easily  accessible  originals  by  Maurizio 


*  The  plate  is  double  and  cannot  be  separated  into  two.  It  should  be  referred  to  as 
plate  4-5. 


62 


THE  SAPROLEGNIACEAE 


in  Flora,  we  shall  not  here  describe  these  five  forms  further  than  is  done 
in  the  following  key  (the  plate  references  are  omitted) : 

Antheridial  cell  very  rarely  cut  off,  but  more  or  less  thread-like  projections  enter  the  oogonia 
from  below.  Stalks  of  oogonia  much  bent.  Pits  small,  numerous  and  conspicuous. 
Eggs  mostly  3-6,  rarely  12-20;  diameter  20-304.  Germination  period  70-80  days 

Var.  I 

Antheridial  cells  rarely  absent  under  the  oogonia. 

Pits  numerous.  Germination  period  of  eggs  70-80  days. 

Antheridial  cells  very  rarely  absent;  under  these  usually  still  other  cells  cut  off.  Eggs 

2  to  over  30;  diameter  18-22.54 . . Var.  II 

Antheridial  cells  always  present,  but  no  other  cells  cut  off  beneath  them.  Not  rarely 
are  formed  lateral  outgrowths  from  the  hypogynous  cell,  which  lay  themselves 
against  the  oogonia,  and  appear  like  androgynous  antheridia.  Eggs  1  to  over 

40,  diameter  15-254 . Var.  Ill 

Pits  fewer,  not  over  4.  Germination  period  39-50  days.  Diameter  of  eggs  18-234. 

Wall  of  oogonium  very  thin,  by  slight  pressure  becoming  flattened.  No  extra  cells 
beneath  the  antheridial  cell.  Eggs  often  polygonal  from  pressure,  mostly  2-10, 

but  up  to  35-50  in  an  oogonium . Var.  IV 

Wall  of  oogonium  stronger:  additional  cells  cut  off  under  the  antheridial  cell.  Antheri¬ 
dial  tubes  1-2,  very  long,  bent,  often  filled  with  plasma.  “Starker  als  bei  irgend 
einer  der  anderen”  varieties.  Eggs  mostly  3-12,  never  more  than  12. 

Var.  V 

Saprolegnia  intermedia  (Form  6  above)  is  said  by  Maurizio  to  be 
nearest  his  Var.  V,  which  agrees  in  the  almost  constant  presence  of  the 
antheridial  cell,  the  well  developed  antheridial  tubes  with  thin  walls 
and  abundant  protoplasm,  and  in  the  small  number  of  pits.  In  the 
thin  wall,  few  pits  and  number  of  eggs,  he  says  it  approaches  his  Var.  IV. 
This  sixth  form  (S.  intermedia )  may  be  briefly  defined  thus; 

Antheridial  cell  almost  always  present;  antheridial  tubes  usually 
well  developed,  single  or  several,  simple  or  branched,  thin-walled,  with 
distinct  protoplasmic  contents,  oogonia  in  groups  on  short  or  long  stalks, 
or  in  chains  or  intercalary,  spherical  or  pear-  or  barrel-shaped;  mem¬ 
brane  thin,  colorless,  in  small  oogonia  without  pits,  in  larger  ones  with 
2-5  pits,  which  are  not  easily  seen  except  with  high  power.  Eggs  6-10, 
or  up  to  40  in  large  oogonia;  diameter  19-234.  Germination  period 
20  days. 

Saprolegnia  hypogyna  var.  Coregoni  Maurizio.  Mitt.  d.  Deutsch. 
Fischerei-Vereins  7:  55.  1899  (Form  7  above).  On  account  of  the  in¬ 
accessibility  of  the  original,  we  give  below  a  practically  complete  trans¬ 
lation  of  Maurizio’s  description  (there  are  no  figures) : 

“Isolated  from  an  egg  of  Coregonus  [pike]  which  came  from  a  fish 
hatchery  on  the  Hallwylersee,  Kt.  Aargau.  Cultivated  for  over  a  year. 
Turf  up  to  1  cm.  long.  Sporangia  as  usual.  Oogonia  intercalary  in 
chains,  or  in  sympodial  arrangement,  or  finally  rather  rarely  in  racemes. 
Stalk  of  moderate  length  and  frequently  remarkably  slender;  when 


SAPROLEGNIA 


63 

arrangement  is  racemose  the  stalk  is  often  so  long  as  to  obscure  the 
arrangement;  spherical  (when  in  racemes),  elongated  or  barrel-shaped 
in  other  arrangements;  wall  thin,  a  little  yellowish,  pits  small,  not  numer¬ 
ous;  diameter  44-77^1.  or  40-7211.  broad  by  50-97^  long.  Eggs  3  (rarely), 
mostly  12—18,  wall  thick,  clear  yellow,  19.5-21(0..  Hypogynous  anther- 
idial  cell  always  present,  no  other  antheridia,  and  no  other  cells  below  it; 
under  small  oogonia  it  is  about  14.5x20(0.,  usually,  however,  about  17-20(0, 
broad  by  24.5-68(0.  long;  fertilizing  tube  (which  is  often  absent)  5-1  ojx 
long,  or  up  to  as  long  as  the  antheridial  cell,  simple  or  branched.  Conidia 
abundant,  spherical  or  elongated,  and  produced  like  the  oogonia,  except 
that  racemes  are  less  distinct.  The  conversion  of  conidia  into  oogonia 
is  a  common  occurrence.” 


14.  Saprolegnia  torulosa  deBary.  Beitr.  zur  Morph,  und  Phys.  der  Pilze, 
IV  Reihe:  31,  pi.  6,  figs.  3-17.1881.  Also  see  Bot.  Zeit.  46:  618. 
1888. 

Saprolegnia  sp.  Lindstedt.  Synopsis  d.  Saproleg.,  p.  48,  pi.  4.  1872. 

This  is  reported  by  Humphrey  from  Massachusetts,  New  Hamp¬ 
shire  and  Louisiana,  but  it  is  doubtful  if  he  had  the  true  species  (see 
remarks  under  Isoachlya  toruloides).  DeBary’s  description  in  Bot. 
Zeitung  is  as  follows: 

“  Primary  sporangia  slender,  cylindrical,  claviform;  oogonia  irregu¬ 
larly  spherical,  elongated,  pyriform  or  cylindric,  seldom  egg-shaped, 
almost  always  appearing  in  torulose  rows  of  two  to  several  by  constric¬ 
tion  of  the  main  hyphae;  after  ripening  remaining  firmly  attached  to 
each  other.  Oogonial  wall  with  few  or  no  pits.  Oospores  centric.  An¬ 
theridial  branches  and  antheridia  usually  completely  absent.  In  the 
rare  cases  where  present  either  androgynous  or  diclinous.  Antheridia 
with  or  without  a  fertilizing  tube. 

“Lip  to  the  formation  of  primary  sporangia  the  species  cannot  be 
distinguished  from  S.  monoica.  Later,  as  already  fully  described  (Beitr. 
IV,  p.  102),  the  main  branches  become  divided  by  cross  walls  into  struc¬ 
tures,  the  outer  of  which  occupy  the  position  to  be  taken  by  the  oogonia. 
Between  these  initials  the  threads  are  constricted  so  as  to  appear  toru¬ 
lose.  Such  appearances  are  also  not  rare  in  old  examples  of  other  spe¬ 
cies,  as  in  the  formation  of  the  sporangial  rows  described  by  Pringsheim 
and  of  resting  cells  [gemmae].  In  the  present  species  certain  of  these 
structures  become  such  sporangia  and  gemmae;  others,  however,  in 
special  position  and  number  become  oogonia,  and  indeed  the  oogonia 
here  are  almost  entirely  formed  from  such  chained  initials.  Single 
oogonia  terminating  the  vegetative  threads  are  occasional  and  such  are 
often  ovate  or  pyriform.  Significant  details  are  fully  described  in  Beitr. 
IV. 

“  The  species  appears  rare.  Found  in  a  stream  near  Strassbourg 
in  April,  1879.  and  cultivated  until  1884.  Also  doubtfully  seen  in  slime 
from  the  Todtensee  near  the  Grimsel.” 


64 


THE  SAPROLEGXIACEAE 


The  species  has  been  found  only  a  few  times.  Recently  Hayr6n 
has  reported  it  from  Finland  and  Gaumann  from  Lapland.  Fischer 
has  a  good  description  with  measurements  (‘92,  p.  340,  fig.  52b).  He 
gives  the  eggs  as  up  to  a  good  many  in  an  oogonium,  14-2210.  thick,  round 
or  at  times  irregular;  antheridia  mostly  absent,  when  present  androgy¬ 
nous  or  diclinous.  He  thinks  that  Lindstedt’s  plate  4  (’72)  of  an  un¬ 
named  species  is  really  this.  For  another  supposed  figure  of  this  see 
Lechmere  (’ua),  fig.  1.  Lechmere  found  that  the  plant  he  studied  formed 
no  oogonia  on  egg  albumen. 

15.  Saprolegnia  asterophora  deBary.  Jahrb.  f.  wiss.  Bot.  2:  189,  pi.  20, 
figs.  25-27.  i860. 

Plate  19 

Mycelium  extensive,  but  thin  and  delicate.  Hyphae  slender,  un¬ 
even,  much  or  little  branched,  about  5— 1 1  p.  thick,  rapidly  thickening 
towards  the  sporangia  which  are  typically  very  scarce  and  often  entirely 
absent  in  cultures  on  insects.  They  are  up  to  4010.  thick,  sub-cylindrical 
to  clavate,  and  proliferate  from  within,  or  rarely  laterally  from  below 
as  in  Achlya.  Spores  14-15^  in  diameter,  emerging  and  swimming 
slowly  and  aimlessly  in  the  neighborhood  for  two  or  three  minutes,  then 
encysting  and  after  a  few  hours  emerging  in  the  usual  form  and  in  a 
more  active  state.  Gemmae  not  abundant,  often  absent  on  insects, 
peculiar,  shaped  like  the  sporangia  or  pear-shaped,  tuberous,  knotted, 
etc.  Oogonia  numerous,  usually  thickly  set  with  blunt  papillae  which 
are  usually  2-4^,  rarely  up  to  8[jl,  long;  oogonia  about  30-57^  thick, 
including  the  papillae,  most  about  37-45^,  borne  on  even  more  slender 
lateral  branches  of  small  ordinary  hyphae  (the  stalks  rather  long),  or 
occasionally  intercalary  or  terminal;  walls  thin  and  unpitted.  Eggs 
one  or  often  two,  rarely  three  (very  rarely  4  or  5 — deBary),  18-3510. 
in  diameter,  dark,  often  a  large  and  a  small  one  together;  structure 
subcentric,  i.  e.,  with  the  protoplasm  completely  surrounded  by  small  oil 
drops,  which  are  in  a  double  layer  on  one  side  and  a  single  layer  on  the 
other.  Antheridial  branches  varying  greatly  in  abundance,  often  nearly 
absent  at  low  temperature,  appearing  close  to  the  oogonium  and  usually 
from  its  stalk,  rarely  from  neighboring  hyphae,  often  branched  and 
several  arising  in  a  twiggy  group,  but  only  one  or  two  becoming  fully 
developed.  Antheridia  short-tuberous  or  pear-shaped;  antheridial  tubes 
not  seen. 

Found  only  three  times  out  of  more  than  two  thousand  collections  in 
Chapel  Hill,  twice  on  the  same  day  (Nos.  4  and  5,  February  14,  1918)  in 
two  places  on  New  Hope  Creek  margin  south  of  the  Durham  bridge;  again 
in  a  wet  weather  branch  in  Strowd’s  lowgrounds,  February  8,  1922.  For 
other  illustrations  see  deBary  (’8i),  pi.  6,  figs.  18-29;  Humphrey  (’92), 
pi.  17,  figs.  54  and  55;  Minden  (’12),  fig.  if  on  p.  520;  Istvanfifi  (’95), 
pi.  35,  figs.  19-21,  and  pi.  36,  fig.  22. 


PLATE  19 


PLATE  19 

Saprolegnia  asteropiiora 

Fig.  i.  Emptied  sporangia  one  on  left  containing  young  oogonium.  X  278. 

Eig.  2.  Irregular  hypha  with  oogouia.  X  188. 

Fig.  3.  Cluster  of  oogonia.  X  188. 

Fig.  4.  Oogonia  and  sporangia.  X  1 88. 

Fig.  5.  Young  oogonia.  X  188. 

Fig.  6.  Spores  sprouting  in  sporangium.  X  188. 

Fig.  7.  Three  gemmae.  X  188. 

Fig.  8.  Oogonium  with  ripe  egg.  X  810. 

Fig.  9.  Proliferation  through  an  old  sporangium  forming  an  oogonium.  X  115. 

Fig.  10.  Zigzag  course  of  hypha  caused  by  death  of  tips.  X  1 1 5. 

Fig.  II.  Oogonium  with  antheridia.  X  503. 

Fig.  12.  Intercalary  oogonium.  X  503. 

Fig.  13.  Chain  of  intercalary  oogonia.  X  503. 

Fig.  14.  Oogonia  with  an  antheridium  and  numerous  aborted  antheridial  branches.  X 

5«3- 


PLATE  iy 


SAPROLEGX IA  ASTEROPHORA 


' 


SAPROLEGNIA 


65 


This  rare  plant  has  been  reported  heretofore  in  America  only  by 
Humphrey  and  by  Pieters.  The  former  did  not  see  the  living  plant, 
but  recorded  it  from  preparations  by  Trelease,  who  found  it  in  eastern 
Massachusetts  (Cambridge  and  Woods  Hole).  Pieters  found  the  plant 
near  Ann  Arbor,  Michigan,  and  its  occurrence  is  noted  in  Ann.  Rep.  Mich. 
Acad.  Sci.  17:  195.  1915.  He  has  kindly  allowed  us  to  examine  his 
unpublished  notes  and  drawings.  The  species  has  been  reported  from 
several  places  in  Germany,  but  seems  to  be  rare  there  also  (Fischer, 
’92,  p.  343). 

This  species  is  distinctly  set  off  from  the  other  members  of  the 
genus  by  its  fine,  irregular  hyphae  and  few-egged,  papillate  oogonia. 
No  other  species  of  Saprolegnia  has  an  average  of  so  few  eggs.  If  it  were 
not  for  the  sporangia  one  would  place  it  near  Aphanomyces  stellatus. 
Its  actual  relationships  are,  however,  probably  with  the  Racemosa  group 
of  Achlya,  particularly  with  A.  hypogyna.  The  tips  of  the  hyphae  are 
blunt  and  very  hyaline,  and  sometimes  die  without  apparent  cause,  the 
hyphae  being  continued  by  a  lateral  branch  just  below,  as  in  certain 
species  of  Achlya.  The  mycelium  grows  to  a  greater  diameter  than  in 
other  species  under  similar  conditions,  but  is  more  thin  and  sparse  than 
others.  The  threads  are  rarely  cylindrical,  but  are  wavy  and  knotted. 

It  is  interesting  to  find  that  Pieters  has  also  observed  the  “slow, 
deliberate  movement”  of  the  discharging  spores  and  the  great  scarcity 
of  the  sporangia  (unpublished  notes).  This  shows  that  these  characters 
are  not  casual  or  accidental.  In  his  notes  Pieters  says  that  in  all  re¬ 
spects  save  only  in  the  method  of  discharge  of  the  sporangia  Achlya 
racemosa  and  Saprolegnia  asterophora  are  quite  similar  and  the  question 
arises  whether  the  latter  is  not  more  closely  related  to  some  species  of 
Achlya  than  it  is  to  other  species  of  Saprolegnia.  He  bases  this  sugges¬ 
tion  in  part  on  the  apparent  absence  of  gemmae  in  his  cultures  of  Sapro¬ 
legnia  asterophora.  We  also  find  them  absent  or  scarce  in  many  cultures, 
while  in  others  there  are  not  a  few.  There  is  no  doubt,  however,  of  the 
striking  similarity  noted  by  Pieters,  and  his  suggestion  may  correspond 
with  the  facts.  He  makes  the  following  interesting  observations  on  this 
species:  “Physiologically  this  species  differs  from  all  other  species  of 
Saprolegnia  studied.  It  thrives  on  extremely  small  quantities  of  food  in 
solution.  If  a  piece  of  mycelium  grown  in  pea  water  is  transferred  to 
water,  and  care  is  not  taken  to  wash  thoroughly,  no  sporangia  are 
produced  but  only  oogonia  and  growth.  In  no  other  Saprolegnia  studied 
have  I  ever  gotten  oogonia  from  a  mycelium  in  water.  If  a  good  culture  of 


66 


THE  SAPROLEGNIACEAE 


Saprolegnia  asterophora  be  transferred  to  haemoglobin,  0.1%  or  0.05%, 
no  oogonia  are  produced;  only  a  vigorous  growth  results,  though  Sapro¬ 
legnia  ferax  will  have  many  after  being  in  0.05%  solution  for  three  days. 
In  0.01%  Saprolegnia  asterophora  produces  a  few  oogonia  after  four  days  but 
not  nearly  so  many  as  are  produced  in  water  in  the  same  time.  The  ex¬ 
planation  for  this  is  merely  that  Saprolegnia  asterophora  does  not  need  so 
much  food  for  growth  as  Saprolegnia  ferax  does,  and  that  therefore  the  small 
amount  of  food  in  0.05%  haemoglobin  is  enough  for  vigorous  growth  and  as 
long  as  there  is  food  enough  for  vigorous  growth  no  oogonia  will  be  produced. 
If  0.05%  of  total  salts  IvH2P04,  MgS04,  and  KN03  in  equal  parts  be 
added  to  the  0.01%  haemoglobin  no  oogonia  are  produced,  but  in  0.01% 
haemoglobin  and  0.01%  salts  a  few  are  found  after  four  days. 

“It  is  of  interest  to  add  that  Achlya  racemosa  which  resembles 
Saprolegnia  asterophora  in  the  number  of  oospores  and  in  the  position 
of  the  antheridia,  and  which  is  sometimes  slightly  spiny,  will  also  pro¬ 
duce  oogonia  in  water.” 

The  ease  with  which  the  number  of  antheridia  can  be  made  to  vary 
would  make  this  a  favorable  species  for  experiment  on  the  causes  for 
such  variation.  DeBary  has  noted  that  in  Saprolegnia  asterophora 
oogonia  without  antheridia  appear  when  the  growth  is  old,  i.  e .,  poorly 
nourished  (on  insects). 

The  production  of  sporangia  is  erratic,  always  limited,  and  often 
entirely  suppressed,  even  for  long  intervals  on  different  media.  In  our 
1922  collection  no  sporangia  ever  appeared,  although  cultivation  was 
continued  on  various  insects  and  vegetable  media  for  several  months. 

Among  many  cultures  made  from  No.  4  of  February  14,  1918,  we 
note  the  following: 

On  corn  meal  agar.  Growth  slower  than  any  other  Saprolegnia  on  agar,  but  threads  are 
thick  in  the  agar  and  rather  stout;  no  sporangia,  but  a  few  oogonia  produced  after 
the  culture  was  several  days  old.  Repeated:  no  sporangia;  oogonia  formed  in  abun¬ 
dance;  a  good  many  antheridia. 

On  pieces  of  boiled  corn.  Growth  vigorous.  Sporangia  produced  but  not  in  abundance; 

a  considerable  number  of  oogonia,  about  half  of  which  had  antheridia. 

At  low  temperature.  Three  young  cultures  on  grubs  put  in  ice  box.  Growth  about 
as  usual;  very  few  sporangia  in  any  one  culture;  oogonia  scattered  and  very  few 
antheridia  present. 


SAPROLEGNIA 


67 


EUROPEAN  SPECIES  NOT  YET  RECOGNIZED  IN  AMERICA. 

Saprolegnia  rhaetica  Maurizio.  Mora  oder  Allgemeine  Botanische  Zeit- 

ung  79:  109,  pi.  3,  figs.  1-16,  and  pi.  4,  figs.  1-4.  1894. 

This  species  is  apparently  near  S.  torulosa  and  possibly  the  same. 
The  next  species  (S.  variabilis)  also  can  scarcely  be  separated  from  these 
by  the  description.  From  A.  torulosa  and  Isoachlya  toruloides  this 
series  differs  most  obviously  in  the  reputed  absence  of  antheridia.  Mau- 
rizio’s  description  follows: 

“Turf  not  very  thick,  up  to  1.5  cm.  long,  with  straight,  slender, 
fragile  and  unbranched  filaments.  Sporangia  apical,  seldom  intercalary. 
Primary  sporangia  small,  clavate,  producing  later  through-growths  of 
varying  lengths  which  usually  tilt  back  over  the  empty  cases  and  take  a 
variety  of  forms. 

“The  fungus  forms  gemmae  [‘conidia’  is  the  word  used  here  and 
below],  which  may  be  arranged  in  rows  or  as  rolls  and  screws.  There 
are  also  complicated  arrangements  of  gemmae  in  no  definable  system. 
In  the  empty  sporangia  gemmae  may  form  by  constriction  (usually) 
or  by  cross  division  in  basipetal  succession.  Corresponding  to  this 
great  variation  in  the  gemmae  noted  is  a  similar  variation  in  the  gem¬ 
mae  found  inside  the  empty  sporangia.  If  the  conidia  are  formed  by 
abstriction  at  the  ends  of  hyphae  the  single  cross  walls,  which  for  some 
time  are  common  to  two  gemmae,  finally  separate  into  two  thin  lamellae, 
one  of  which  surrounds  the  conidia,  the  other  forming  a  connecting 
sheath.  By  such  a  sheath  are  connected  often  a  number  of  gemmae 
in  a  row.  After  some  time  the  connections  between  the  gemmae  break 
down  and  the  single  gemmae  lie  free  in  the  water  by  hundreds. 

“There  are  gradations  between  sporangia  and  gemmae  in  that  a 
part  of  the  gemmae  become  sporangia.  Also  a  part  of  the  gemmae 
may  become  oogonia.  The  formation  and  emptying  of  the  zoospores 
is  the  same  in  the  sporangia  and  the  gemmae.  The  spores  swim  more 
than  one-half  hour.  The  small  oogonia  are  mostly  spherical,  and  when 
apical  and  intercalary  somewhat  elongated.  When  they  develop  from 
gemmae  they  stand  in  rows  and  may  develop  in  the  same  row  with  spor¬ 
angia,  otherwise  they  are  arranged  in  clusters  on  short  stalks.  1  heir 
diameter  is  48-61.5^.  Wall  is  thin,  colorless,  then  yellowish  and  has  2, 
seldom  3,  pits.  From  the  wall  below  the  oogonium  there  generally 
grows  up  into  the  oogonium  a  protuberance  that  may  remain  hollow  or 
may  be  closed  with  a  cellulose  plug.  I  hese  growths  are  not  antheridia, 
which  in  this  species  are  not  present  and  were  not  even  seen.  Oospores 
up  to  12  in  number,  but  mostly  one  to  five.  I  hey  have  only  a  moder¬ 
ately  thick  membrane  and  a  centric  structure.  I  heir  diameter  varies 
between  19  and  27.5:0..  Germination  not  seen.” 

Saprolegnia  variabilis  Minden.  Krypt.  Mora  Mark  B.  5:  524.  1912. 

“Turf  thick,  formed  of  rather  thin,  slender,  little  branched  or  simple 
threads  22—27(0.  thick.  Primary  sporangia  variable  in  size,  spindle,  or 


68 


THE  SAPROLEGNIACEAE 


club-shaped  or  spherical,  formed  in  large  numbers,  mostly  on  smaller 
threads,  e.  g.,  6ox8o;x  or  57x704.  Later  the  threads  fall  into  more  or 
less  numerous  structures  in  rows,  which  become  sporangia,  oogonia 
or  gemmae,  so  that  chains  of  oogonia  or  sporangia  pure  or  mixed  result. 
There  occur  also  structures  in  more  or  less  sympodial  arrangement; 
often  on  the  ends  of  hyphae  are  swollen  sporangia  or  oogonia  or  both; 
oogonia  also  occur  in  empty  sporangia.  Form  of  secondary  sporangia 
very  various;  often  when  in  rows  there  is  a  lower  stalk  piece  and  an 
upper  swollen  part;  or  they  may  be  spherical  with  a  slender  discharge 
neck.  Oogonia  spherical  or  seldom  more  or  less  elongated  with  rather 
thick  membrane  and  a  few  not  conspicuous  pits,  often  with  a  solid  pro¬ 
jection  from  the  wall  below;  diameter  50-704,  or  also  70x904  or  40x604. 
Eggs  spherical  1— 1 5,  mostly  4-8,  23-264  thick;  position  of  the  oogonia 
as  various  as  the  sporangia;  antheridia  never  observed. 

“Hamburg;  on  ant  eggs  in  a  swamp;  several  times  found  and  long 
cultivated  pure.  The  species  is  related  to  S.  torulosa  as  well  as  to  5. 
monilifera.  When  the  oogonia  occur  in  chains  they  remind  one  of  the 
last  species  where  such  an  appearance  is  typical.  We  can  state  cer¬ 
tainly,  however,  that  this  species  is  different.”  He  goes  on  to  say  that 
this  is  very  near  perhaps  identical  with  S.  rhaetica  Maurizio,  of  which 
he  can  not  get  a  clear  idea  from  description  and  figures.  Minden  gives 
no  figures. 

In  one  form  observed  by  Minden  certain  branched  twigs  occur 
rather  numerously  and  appear  like  antheridial  branches,  but  do  not 
apply  themselves  to  oogonia. 

Saprolegnia  crustosa  Maurizio.  (A  group  species.)  Mitt.  d.  Deutsch. 

Fischerei-Vereins  7:  52.  1899. 

This  species  includes  three  varieties,  none  of  which  is  indicated  as 
the  typical.  It  is  therefore  a  question  if  Maurizio’s  arrangement  can 
stand  as  he  has  it.  He  calls  this  “  Sammelspecies  der  Saprolegnia  crus¬ 
tosa  sp.  nov.”  There  are  no  figures.  He  says:  “We  could  consider 
the  three  varieties  here  described  as  good  species,  were  we  not  already 
familiar  with  such  numerous  representatives  of  this  genus  that  are  so 
closely  related.  Sooner  or  later,  the  extension  of  our  knowledge  of  the 
water  fungi  will  lead  to  a  more  systematic  arrangement.  The  discovery 
of  conidia  in  the  genus  Saprolegnia  looks  necessarily  to  a  change  in  the 
classification  of  deBary.  The  fungus  here  described,  which  also  bears 
conidia,  cannot  be  in  any  way  placed  in  the  system  of  deBary  or  of  Fischer 
in  Rabenhorst’s  Krypt.  Flora.  I  refer  to  S.  paradoxa  sp.  nov.,  S.  f ar¬ 
eata  sp.  nov.  and  the  earlier  described  species  with  conidia.  In  spite 
of  the  authoritative  work  of  Fischer,  it  is  my  opinion  that  we  have  here 
a  new  group.* 

*This  kind  of  talk  is  a  good  illustration  of  Maurizio’s  unbalanced  judgment.  There 
is  nothing  to  his  great  claim  of  having  found  conidia  in  the  Saprolegniaceae. 


SAPROLEGNIA 


69 


“The  three  varieties  show  an  identical  arrangement  of  the  oogonia 
and  are  distinguished  by  diclinous  antheridia,  which  are  either  con¬ 
stantly  present,  or  are  more  or  less  abundant.  They  show,  however, 
no  agreement  in  the  diameter  of  the  oogonia  and  eggs,  or  in  the  thick¬ 
ness  of  the  oogonial  wall.  According  to  Fischer’s  principle  of  classifica¬ 
tion,  i.  e.,  from  the  presence  of  diclinous  antheridia,  we  must  place  the 
three  species  [meaning  his  three  varieties]  in  the  neighborhood  of  5. 
dioica,  though  in  this  species  the  diameter  of  the  oogonia  is  not  given: 
however,  in  the  egg  diameter  my  No.  Ill  alone  comes  near,  22-294 
against  25—304  for  A.  dioica.  This  is,  however,  only  of  limited  signifi¬ 
cance.  Again,  the  position  of  the  oogonia — here  racemed  to  clustered, 
terminal  or  intercalary,  simple  or  in  rows — is  still  another  common 
character  that  associates  the  fungi  in  question.  The  name  given  is 
intended  to  show  the  fact  that  two  of  these  fungi  were  isolated  from 
the  crust  of  fungi  that  covered  water  pipes.” 

The  following  descriptions  are  condensed  from  Maurizio: 

Saprolegnia  crustosa  var.  I.  p.  52. 

Isolated  from  a  varied  growth  on  the  thin  shell  of  a  freshly  caught 
mussel  (. Anodonta  mutabilis )  and  cultivated  for  a  year.  Growth  dense, 
2  cm.  long.  Sporangia  as  usual.  Oogonia  racemose  or  clustered,  also 
intercalary;  and  also  in  simple  sympodia  of  2  or  4;  spherical  or  elon¬ 
gated  at  times,  if  intercalary;  stalk  short,  straight,  of  moderate  thick¬ 
ness,  membrane  somewhat  yellowish,  of  medium  thickness,  with  pits 
of  medium  size  that  are  not  numerous;  frequently  an  upgrowth  enters 
the  oogonium  from  the  wall  below;  diameter  of  oogonia  31. 5-604  or  when 
elongated  33-41  [j.  broad  by  50-554  long.  Eggs  4-25,  various  in  size, 
mostly  1 9.5— 22[x,  smallest  124;  wall  moderately  thick  and  yellowish, 
Antheridia  mostly  present,  diclinous,  coming  from  a  distance,  and  plenti¬ 
fully  enveloping  the  oogonia,  not  observed  to  branch.  In  this  species, 
as  in  all  the  species  examined  by  me,  conidia  are  present,  in  rows  or 
chains,  also  in  complicated  sympodia,  rarely  single,  becoming  either 
sporangia  or  oogonia,  or  resting.  There  are  also  present  in  the  con¬ 
idia  the  tubes  from  the  cross  wall  below,  as  in  the  oogonia. 

Saprolegnia  crustosa  var.  II.  p.  53. 

As  with  S.  furcata  and  the  following  variety,  this  was  found  in  the 
layer  of  fungi  that  covered  the  inside  of  the  outlet  pipe  of  an  aspirator. 
Cultivated  for  a  year.  The  dense,  if  rather  slender,  threads  about  1.5 
cm.  long  on  a  mealworm.  Hyphae  and  sporangia  not  peculiar.  Oogonia 
in  racemes  and  clusters,  mostly  spherical,  39-104. 54  thick,  stalks  moder¬ 
ately  slender.  The  elongated  intercalary  ones  were  not  measured  be¬ 
cause  so  rare;  membrane  very  thin  and  colorless,  pits  not  numerous, 
moderately  broad,  not  deep;  wall  yellowish,  after  long  standing  in  water. 
Eggs  1-5  in  small  oogonia,  9—20  in  large  ones,  17-27^  thick,  almost 
filling  the  oogonia,  their  membrane  thick  and  somewhat  yellowish.  An¬ 
theridia  numerous,  diclinous;  entire  thread-ends  break  up  into  antheridial 


70 


THE  SAPROLEGNIACEAE 


branches,  which  then  plainly  enwrap  the  oogonia.  Here  and  there 
fertilizing  tubes  to  be  seen:  conidia  produced  in  abundance  in  chains 
or  rows,  or  racemes,  with  manifold  side  branches,  also  in  empty  sporangia; 
many  chains  visible  to  naked  eye,  some  1-1.5  mm.  long. 

Saprolegnia  crustosa  var.  III.  p.  54. 

Found  in  same  place  as  var.  II.  A  somewhat  denser  turf  than  in 
var.  II  distinguish  the  two  nearly  related  species;  hyphae  1.5  cm.  long; 
rather  flexible,  but  standing  out  straight.  Sporangia  as  usual.  In 
cultures  on  mealworms  and  ant  larvae  there  occur  at  the  beginning 
neither  the  sporangia  nor  oogonia.  Slowly  the  fungus  strengthens  itself 
in  the  culture  and  forms  the  turf,  which  does  not  disappear.  Oogonia 
racemose,  or  also  terminal  or  intercalary,  stalks  very  unlike,  and  the 
arrangement  thus  of  very  different  appearance.  They  are  short,  or  at 
times  so  long  as  scarcely  to  be  recognized  as  oogonial  stalks.  Oogonia 
mostly  spherical,  seldom  elongated,  membrane  of  medium  thickness; 
pits  numerous,  small,  sharply  defined.  Diameter  of  oogonia  73-121.54, 
rather  regular  (small  ones  with  1-3  eggs  are  rare).  Hollow  tubes  not 
rarely  enter  the  oogonia  from  below.  Eggs  20-50,  wall  thin,  almost 
colorless,  thickness  nearest  that  of  S.  dioica,  being  22-294.  Antheridia 
diclinous,  only  on  about  one-third  of  the  oogonia.  Conidia  various  in 
position  and  form;  spherical,  barrel-shaped  to  long-compressed  and  thread¬ 
like,  often  difficult  to  describe,  enormously  various  in  size,  30  to  300 
or  5004  thick.  Position  of  the  conidia  very  various,  in  chains  with 
sporangia,  also  with  side-branches,  also  sympodial  or  irregularly  tangled, 
and  thus  most  resembling  S.  rhaetica,  often  in  empty  sporangia.  Oogonia 
may  also  be  formed  at  times  (not  often)  in  empty  sporangia. 

Saprolegnia  stagnalis  Tiesenhausen.  Arch.  f.  Hydrobiol.  und  Plankton- 

kunde  7 :  276.  1912. 

Found  in  a  ditch  near  St.  Moritz,  in  Oberengadin,  Switzerland. 

“Turf  delicate,  about  2  cm.  broad,  sporangia  usually  rather  slender, 
e.  g.,  260x294,  500x204,  720x454,  or  even  80x204  in  size.  The  sec¬ 
ondary  through-growing  sporangia  are  constricted  (i.  e.,  grow  through 
the  older  ones  and  are  pinched  in  by  their  mouths).  Oogonia  25-804 
in  diameter,  terminal  on  the  principal  branches  and  on  side  branches, 
sometimes  on  branches  of  the  second  order,  also  inside  empty  sporangia 
or  in  a  row  by  twos  (zu  zweien) ;  wall  with  numerous  pits  that  are  even 
visible  in  surface  view;  stalks  short  and  often  bent.  Eggs  as  a  rule  con¬ 
centric,  12-22.54,  exceptionally  32.5x154;  1-12  in  an  oogonium.  One 
or  two  eggs  in  an  oogonium  occur  frequently.  Antheridia  always  di¬ 
clinous.” 

The  author  remarks  that  the  species  differs  from  S.  dioica  (S.  di- 
clina)  principally  in  four  points:  (1)  The  constricted  sporangia  (the 
sporangia  of  S.  dioica  do  not  grow  beyond  the  older  ones).  (See  deBary, 
’88,  p.  619,  pi.  10,  fig.  13.)  (2)  In  S',  dioica  the  oogonia  appear 

only  on  the  tips  of  the  main  branches,  while  in  S.  stagnalis  they  also 


SAPROLEGNIA 


71 


occur  on  side  branches.  (3)  The  oogonial  wall  in  5.  dioica  has  only  a 
few,  or  no  pits,  in  S.  stagnalis  there  are  many  large  pits  visible  at  80 
times  magnified.  (4)  The  eggs  are  smaller  (12-22.54)  than  those  of  5. 
dioica  (25-304).  There  are  no  illustrations. 


Saprolegnia  spiralis  Cornu.  Ann.  Sci.  Nat.,  Series  5,  15:  10,  pi.  6,  figs. 

10-12  and  15-17;  pi.  7,  figs.  1-4  and  10.  1872. 

?  Saprolegnia  retorta  Horn.  Ann.  Myc.  2:  233,  fig.  21.  1904. 

Minden  thinks  he  has  found  Cornu’s  imperfectly  described  species 
and  that  it  is  the  same  as  Horn’s  A.  retorta.  Horn’s  figure  is  good,  but 
as  Minden’s  description  is  more  complete,  we  append  a  translation  of  the 
latter  (Krypt.  FI.  Mark  B.  5:  517.  1912): 

“Turf  thick,  with  long,  slender  threads  11-164  thick,  which  are 
more  or  less  crooked  or  bent  and  have  slightly  granular  contents.  Spor¬ 
angia  of  various  shapes,  cylindrical,  spindleform,  spherical,  etc.,  about 
30-404  thick  and  200-3004  long;  secondary  sporangia  few,  growing 
through  the  old  or  formed  also  by  cymose  branching,  oogonia  either 
on  the  tips  of  main  threads  or  on  short  side  branches  which  are  mostly 
bent,  or  spiral  or  sinuous;  not  rarely  the  oogonia  are  also  intercalary 
and  then  elongated;  oogonia  rarely  quite  spherical,  mostly  elliptic  or 
ovate,  at  times  with  a  blunt  extension  at  the  tip,  usually  with  a  small 
basal  neck,  wall  moderately  thick,  slightly  or  not  at  all  pitted;  on  the 
average  50x654,  or  also  for  example  38x464.  Antheridia  always 
present  and  usually  numerous,  irregularly  cylindric  to  clavate,  touch¬ 
ing  the  oogonium  with  the  entire  length  or  only  with  their  tips,  borne 
on  branches  which  spring  either  from  the  stalk  of  the  oogonium  or  from 
the  main  thread,  often  numerous  and  much  branched,  and  after  ma¬ 
turity  quickly  becoming  inconspicuous.  Eggs  mostly  1-2,  seldom  3  or 
even  4,  smooth,  spherical  or  when  several  more  or  less  elongated,  at 
maturity  with  one  or  many,  mostly  lateral  fat  drops  and  therefore  more 
or  less  plainly  eccentric;  diameter  264  or  for  example  34 x  45lJ- 

“Found  in  spring  in  several  places  near  Hamburg,  Germany,  mostly 
in  company  with  other  species  of  Saprolegnia.  Resembles  S.  monoica 
in  androgynous  antheridia,  but  differs  so  clearly  in  the  position  of  the 
oogonia,  the  small  number  of  eggs  and  the  crooked  stalks  as  to  be  easily 
distinct.  Its  identity  with  S.  spiralis ,  while  not  certain,,  is  made  very 
probable  by  the  few  eggs,  the  crooked  stalk,  and  the  opinion  of  Cornu 
that  his  plant  was  near  S.  monoica." 

Cornu  refers  to  Braun’s  pi.  5,  fig.  22  (’55),  as  representing  his  plant, 
His  own  figures  show  only  parasitized  parts. 

Horn  states  that  in  his  plant  the  oogonia  are  very  numerous,  un¬ 
pitted,  30-754  thick;  the  eggs  1-8  in  an  oogonium,  20-254  thick,  with  a 
central  fat  drop.  This  plant  may  be  different  from  the  one  Minden 
describes  above.  (See  note  under  S.  litoralis.) 


7  2 


THE  SAPROLEGNIACEAE 


Saprolegnia  furcata  Maurizio.  Mitt  d.  Deutsch.  Fischerei-Vereins  7:48, 

figs.  13-15-  1899. 

The  following  is  a  complete  translation  except  for  one  or  two  sen¬ 
tences  of  no  importance.  By  the  “conidia”  he  refers  to  what  are  prop¬ 
erly  known  as  gemmae  or  chlamydospores: 

“  Found  in  a  crust  inside  the  outlet  pipe  of  an  aspirator  in  the  labora¬ 
tory,  and  cultivated  for  over  a  year.  Turf  thin,  only  0.5  cm.  long  on 
a  mealworm,  hyphae  5-1 8;x  thick,  frequently  as  slender  or  more  so  than 
the  stalks  of  the  oogonia,  e.  g.,  in  several  cases  the  stalks  of  the  entire 
oogonial  group  were  only  7-12^4  stalks  with  short,  lateral  outgrowths 
that  give  them  a  knotted  appearance.  Sporangia  proliferating  as  usual. 
Conidia  present.  Frequently  the  zoospores  do  not  escape,  but  sprout 
inside,  through  the  sporangial  wall.  Oogonia  in  racemes,  or  one-sided 
racemes,  or  they  may  be  reduced  to  one;  not  in  a  true  fascicle.  A  peculi¬ 
arity  of  this  species  is  that  the  branch  of  the  always  present  antheridium, 
after  it  has  enwrapped  an  oogonium,  may  divide  and  bear  an  oogonium 
on  its  end.  Such  an  oogonium  can,  for  its  part,  have  an  antheridium 
of  its  own.  It  is  usually,  but  not  always,  a  solitary  oogonium  that  shows 
this  peculiarity.  If  the  oogonial  and  antheridial  stalks  are  equally 
thick,  it  appears  as  if  the  hypha  forked,  carrying  an  oogonium  on  one 
branch  and  an  antheridium  on  the  other  which  does  not  form  a  fertilizing 
tube.  Instead  of  a  fertilizing  tube,  the  antheridium  forms  an  oogonium 
on  its  end.  Oogonia  small,  24.5-41.5tx  thick,  almost  always  round,  inter¬ 
calary  elongated  ones  rare;  borne  on  slender,  short  or  rather  long,  much 
bent  or  wound  stalks.  Wall  yellowish,  pits  small,  not  very  obvious  or 
projecting.  A  tube  often  enters  from  the  wall  below.  Eggs  1-9,  wall 
thin,  clear  yellow,  19.5-22^  in  diameter.  Antheridia  on  almost  all  oogo¬ 
nia,  androgynous,  springing  either  from  the  stalk  of  the  oogonium  or 
the  thread  that  bears  it.  They  branch  frequently  and  attach  them¬ 
selves  to  the  oogonia.  Conidia  occur  here  as  described  for  S.  paradoxa, 
and  have  no  marked  peculiarities.  On  the  conidia  undeveloped  antheridia 
were  observed. 

“The  species  shows  several  similarities  to  S.  mixta.  The  latter 
is  an  intermediate  form  between  S.  Thureti  and  S.  monoica,  and  it  must 
be  emphasized  that  our  species  is  decidedly  not  related  to  A.  Thureti. 
Saprolegnia  furcata  has  distinctly  smaller  oogonia  than  S.  monoica  and 
differs  from  it  further  in  the  occurrence  of  the  forks  which  bear  an 
antheridium  and  an  oogonium.  As  this  is  a  constant  peculiarity  found 
in  all  cultures,  it  must  allow  this  species  to  be  distinguished  as  new, 
and  it  may  be  known  as  S.  furcata." 

Saprolegnia  curvata  Minden.  Krypt.  Flora  Mark  B.  5:  609.  1915. 

The  following  is  a  much  condensed  description  of  this  interesting 
species,  made  from  the  rather  long  original  in  German.  The  sluggish 
spores  and  oogonia  in  chains  would  suggest  that  this  species  might 
more  properly  fall  in  the  genus  Isoachlya ; 


SAPROLEGNIA 


73 


Found  on  the  egg  mass  of  a  snail  ( Bunynia )  at  Hamburg,  Germany. 
It  is  peculiar  in  having  the  sporangia  spiral  or  bent,  in  the  very  large  (25^) 
spores  with  a  very  short  and  sluggish  first  swimming  stage,  and  in  the 
oogonia  being  borne  inside  the  substratum  (egg  mass).  Oogonia  terminal 
or  mostly  intercalary,  at  times  many  in  a  row,  seldom  approaching 
spherical,  mostly  only  swollen  places  in  the  hyphae  and  very  irregular 
and  unsymmetrical  with  bent  in  or  projecting  places  in  the  membrane. 
Antheridia  numerous,  borne  on  long,  sinuous,  much-branched  threads 
(whether  androgynous  or  diclinous  is  not  stated).  Eggs  up  to  10,  mostly 
3-5,  at  times  only  one  [size  not  given]. 

Saprolegnia  lapponica  Gaumann.  Botaniska  Notiser,  p.  156.  1918. 

This  species  is  near  5.  esocina  and  S.  ferax.  As  described  it  differs 
from  the  latter  in  the  smaller  eggs  and  in  oogonia  rarely  ever  termin¬ 
ating  the  main  hyphae.  The  following  is  a  free  translation  from  the 
original  (there  are  no  figures) : 

“From  a  puddle  at  the  foot  of  the  Nuolja  [Lapland!,  I  isolated 
a  form  which  belongs  in  the  S.  Thureti  group,  but  which  cannot  be  identi¬ 
fied  with  any  of  the  so-far  described  species.  While  the  typical  Thureti , 
as  Fischer  correctly  observed,  has  terminal  oogonia,  those  of  lapponica 
are  borne  laterally  and  are  mostly  at  a  considerable  distance  from  one 
another  and  from  the  ends  of  the  hyphae.  The  latter  can  be  identified 
(even  with  the  unaided  eye)  by  the  pretty  turf,  in  which  the  oogonia 
occupying  the  inner  zone  cause  a  white  field  to  stand  out;  later,  in  old 
exhausted  cultures,  this  character  is  obliterated,  in  that  oogonia  may 
be  found  farther  out  and  occasionally  even  terminal  as  in  the  typical 
form.  Yet  this  character  of  the  oogonia  being  (normally)  borne  later¬ 
ally  on  the  hyphae  has  remained  constant  through  nine  generations. 

“Over  against  the  two  other  species  of  the  Thureti  group,  namely, 
A.  esocina  and  S.  bodanica ,  the  demarcation  is  harder  to  make  good. 
As  to  the  size  of  the  oospores,  S.  lapponica  agrees  strikingly  with  S. 
esocina ,  in  that  the  majority  of  the  oospores  (91  out  of  100)  are  21-24'j. 
thick.  It  can  readily  be  separated,  however,  from  A.  esocina  by  the 
brown  (not  colorless)  oospore  membrane  and  by  the  absence  of  oogonia 
in  chains.  ”  [Gaumann  is  mistaken  here,  for  Maurizio  says  oogonia  in 
chains  are  not  found  in  his  species.] 

“On  the  other  hand  A.  lapponica ,  through  its  lateral  oogonia,  re¬ 
minds  one  of  S.  bodanica.  I  purposely  at  this  place  avoid  the  expression 
of  a  racemose  oogonial  order,  since  it  could  give  an  incorrect  conception 
of  its  appearance  in  regard  to  S.  monoica.  The  oogonia  are  less  numer¬ 
ous,  averaging  three  to  five  on  each  hypha;  often  situated  far  apart  and 
occasionally  even  on  the  same  side.  W  hile,  furthermore,  the  oogonia 
of  S.  bodanica  are  often  borne  on  long  stalks  (see  Maurizio,  pi.  2,  fig.  52. 
1896),  in  A.  lapponica  the  oogonia  are  mostly  borne  on  short  stalks  or 
are  even  sessile  on  the  main  hyphae.  hurthermore,  and  this  is  the  main 
point  of  distinction,  the  oospores  of  S.  bodanica  measure  in  general  23.5- 
2,1  [x,  while  S.  lapponica,  as  noticed  above,  vary  normally  from  2 1-24^. 

“These  grounds  caused  me  to  separate  the  form  in  question  as  an 
individual  species,  which  perhaps  may  be  synonymous  with  the  S.  Thureti 


74 


THE  SAPROLEGXIACEAE 


form  V,  of  Minden  (1912,  p.  523).  By  all  means  this  complicated  and 
often  unclear  systematic  situation  summons  one  (as  was  the  opinion 
of  deBary)  to  investigate  again  the  extent  of  variability  of  the  species 
of  the  Saprolegniaceae.  The  diagnosis  of  the  species  follows: 

‘‘Turf  delicate,  extending  1-2  cm.  on  a  fly;  hyphae  slender,  straight, 
sparingly  branched,  8-1410.  thick;  zoosporangia  slightly  greater  in  diam¬ 
eter  than  the  hyphae,  terminal;  antheridia  absent;  oogonia  lateral,  borne 
on  a  short  stalk  or  sessile,  a  tube-like  growth  from  the  oogonial  stalk 
often  proliferating  up  into  the  oogonium;  diameter  of  oogonia  45-7511; 
pits  distinct,  of  unequal  frequency  (6-18  in  oogonia  on  same  hypha) ; 
eggs  globose  or  broadly  ellipsoid,  tawny-colored,  19-314,  usually  21-244, 
in  diameter,  1— 1 8  in  each  oogonium.” 

Saprolegnia  mixta  var.  Asplundii  Gaumann.  Botaniska  Notiser,  p. 
155.  1918. 

This  is  said  to  differ  from  the  typical  form  (in  the  sense  of  Maurizio, 
1895)  only  in  the  smaller  oospores,  which  vary  from  15-21 4,  mostly 
16-194,  thick  (no  figures). 

Saprolegnia  floccosa  Maurizio.  Mitt.  d.  Deutsch.  Fischerei-Vereins  7: 

50,  figs.  16  and  17.  1899. 

The  following  is  a  translation  from  the  original,  complete  except 
for  the  omission  of  a  few  unimportant  words: 

‘‘This  species,  like  S.  paradoxa,  was  isolated  from  eggs  of  the  Amer¬ 
ican  brook  trout  at  Munchhausen  hatchery,  in  the  winter  of  1895.  Cul¬ 
tivated  for  iT>  years.  Turf  very  delicate,  and  1.5-2  cm.  long.  It  spreads 
out  and  floats  in  a  flocculent  manner  on  the  water.  This  quality  sug¬ 
gested  the  name.  Sporangia  growing  through  as  usual,  and  not  peculiar. 
Oogonia  in  racemes  or  intercalary;  there  also  occur  sympodia  of  a  few 
oogonia;  spherical,  only  the  intercalary  and  terminal  ones  are  elongated 
or  barrel-shaped :  the  flattened  or  angular  appearance  of  small  oogonia 
I  attribute  to  the  sharply  projecting  pits.  The  mostly  short  oogonial 
stalks  are  contracted  at  the  base;  they  are  straight  or  a  little  bent,  never 
wound;  membrane  only  moderately  thick;  small  projections  enter  the 
oogonia  from  below;  pits  numerous,  small,  sharply  springing  outward, 
to  this  fact  is  due  the  angles  and  depressions  of  the  oogonia;  diameter 
45.5-734.  Eggs  1— 1 5,  usually  4-9,  wall  thin,  diameter  24-25.64.  An¬ 
theridia  on  about  three-quarters  of  the  oogonia,  arising  from  their  stalks 
or  from  the  hyphae  near  them,  thickly  applied  to  the  oogonia.  Conidia 
[meaning  gemmae]  present,  in  chains  or  complicated,  often  also  more 
or  less  racemose  with  the  oogonia,  therefore  they  may  be  considered 
the  original  fruit-form  from  which  the  oogonia  sprang,  often  with  a 
slender  projection;  form  various,  e.g.,  often  narrow  in  a  thread-like  way. 
In  the  system  the  species  falls  in  the  Fercix  group  and  also  approaches 
in  many  points  S.  dioica.  It  is  distinguished  from  it  by  the  racemose 
oogonia  and  by  the  androgynous  antheridia.  Eggs  somewhat  smaller 
than  in  S.  dioica.  The  diameter  of  the  oogonia  agrees  pretty  well  with 


SAPROLEGNIA 


/  O 

that  of  S.  monoica,  but  the  latter  has  distinctly  smaller  eggs.  In  S.floccosa 
we  have,  therefore,  a  new  species  of  the  Ferax  group.” 

It  is  evident  from  the  above  that  this  species  is  very  near  if  not 
the  same  as  5.  monoica  var.  giomerata ,  about  the  only  apparent  difference 
being  the  bulging  out  of  the  egg  membrane  at  the  pits. 

Saprolegnia  monoica  var  montana  deBary.  Bot.  Zeit.  46:  617.  1888. 

DeBary  says:  “This  differs  from  the  typical  form  in  the  abundant, 
irregularly  arranged  and  longer  stalks  of  the  oogonia;  in  the  longer  and 
more  slender  branches,  and  in  the  somewhat  thicker  oogonial  wall  with 
few  or  no  pits.” 

Saprolegnia  paradoxa  Maurizio.  Mitt.  d.  Deutsch.  Fischerei-Vereins  7, 

heft  I:  46,  figs.  10,  11,  12.  1899. 

Not  S.  paradoxa  Petersen. 

The  typical  form,  found  on  eggs  of  sea  trout  in  the  fish  hatchery 
at  Munchhausen,  Reg.  Bez.,  Cassel,  has  androgynous  antheridia  in  a 
group  below  the  oogonia;  eggs  9-30  in  an  oogonium,  25-274.  thick,  or  in 
the  small  oogonia  17-22(0.;  oogonia  terminal  or  intercalary,  more  or  less 
racemosely  borne,  spherical  to  long  barrel-shaped  or  even  thread-like 
with  a  row  of  eggs  (thread-like,  egg-containing  extension  of  oogonia 
are  not  rare  in  5.  ferax ) ;  often  with  a  solid  or  hollow  process  running 
in  from  the  wall  below  as  so  frequently  happens  in  the  Ferax-Monoica 
group;  wall  of  oogonium  not  very  thick,  pits  distinct.  A  very  great 
oddity  is  the  fact  that  the  antheridial  branches,  which  not  rarely  spring 
from  the  long,  neck-like  extension  of  the  oogonia,  may  in  such  cases 
contain  eggs. 

This  species  is  obviously  near  S.  monoica ,  from  which  it  seems  to 
differ  in  the  apical  extension  on  many  of  the  oogonia  and  possibly  in 
other  ways.  It  is  much  like  our  S  litoralis,  in  which  such  extensions  are 
frequent,  but  the  latter  has  much  larger  eggs. 


EXCLUDED  OR  DOUBTFUL  SPECIES  NOT  MENTIONED  IN  THE  TEXT 

Saprolegnia  xylophila  Kiitz.  Phycologia  Generalis.  Lipsiae,  1843-  NTo  Information  is 
given  that  could  define  the  species. 

5.  minor  Kiitz.  (1.  c.,  1843)  is  probably  an  Empnsa. 

S.  deBaryi  Walz.  Bot.  Zeit.  28:  537.  1870.  Probably  a  Pythium:  not  a  Saprolegnia. 

S.  siliquaeformis  Reinsch.  Jahrb.  f.  wiss.  Bot.  11:293.  1878.  This  is  Monoblepharis  prolif- 
era,  according  to  Cornu  and  Fischer. 

5.  Schachtii  Frank.  Krankheiten  der  Pilzen,  p.  384.  Berlin,  1881.  This  is  probably 
P vthium  deBar van um. 


76 


THE  SAPROLEGNIACEAE 


5.  Libertiae  (Borv)  Kiitz.  Species  Algarum.  Lipsiae,  1849.  This  is  thought  by  Fischer 
to  be  Apodya  lactea.  Too  imperfectly  described  to  distinguish  are  5.  Candida,  S. 
tenuis  and  5.  saccata  published  at  the  same  time  by  Kiitzing. 

5.  mucophaga  Smith.  Gardeners  Chron.  22:  245,  fig.  50.  1884.  Not  a  Saprol-egnia ; 
possibly  a  Pytliium. 

S.  philomukes  Smith.  Gardeners  Chron.  22:  245.  1884.  Illustrated  in  the  same,  20: 
781,  fig.  140.  1883.  Not  a  Saprolegnia',  possibly  a  Pythium. 

S.  corcagiensis  Hartog.  Quart.  Jour.  Mic.  Sci.  27:  429.  1887.  Said  to  be  constricted  as 
in  Leptomitus  and  with  similar  sporangia,  but  with  oogonia.  Needs  further  study. 

S.  quisquiliarum  Roumeg.  Fungi  Selecti  Exsiccati.  Cent  60,  No.  5932.  1891.  Humph¬ 
rey  states  that  the  specimen  fails  to  show  anything  in  this  family. 

S.  elongata  Massee.  British  Fungi,  p.  217.  1891.  Apparently  based  on  mixed  mate¬ 
rial,  in  part  a  Pythium  and  in  part  a  Saprolegnia. 

S.  sp.  (Pieters  No.  66.)  Bot.  Gaz.  60:  483.  1915.  This  is  a  sterile  Saprolegnia  from 
Michigan  studied  by  Pieters  for  eighteen  months.  It  yielded  abundant  harvests  of 
round  single  gemmae  but  no  oogonia. 


APLANES  deBary,  1888,  p.  613. 

This  genus  was  established  by  deBary  on  a  single  character,  the 
absence  of  any  swimming  stage  in  the  spores,  which  remain  in  the  spor¬ 
angium  and  sprout  there  by  germ  tubes  through  the  sporangial  wall ; 
otherwise  as  in  Achlya.  There  has  always  been  some  uncertainty  about 
the  sporangia,  as  Reinsch’s  Achlya  Braunii  which  was  considered  the 
same  as  Aplanes  by  deBary  was  described  as  having  dictiosporangia,  the 
spores  emerging  singly  through  the  sporangial  wall  and  leaving  behind  a 
“cell  net”  which  quickly  disappeared.  Reinsch  writes  in  a  confused  way 
about  the  sporangia  and  one  of  his  figures  (as  well  as  the  explanation 
of  figures)  distinctly  contradicts  his  statements,  as  it  shows  two  sporangia 
with  distinct  papillae  of  emergence  as  in  Saprolegnia  or  Achlya.  Still 
further  confusion  is  caused  by  his  reference  under  A.  Braunii  in  the  text 
to  a  figure  (pi.  14,  fig.  9)  showing  four  empty  sporangia  emptying  as  in 
Achlya ,  but  in  the  explanation  of  figures  putting  it  under  Saprolegnia 
sp.  No.  2.  On  page  287  he  says  that  the  sporangia  are  usually  borne 
on  threads  that  do  not  bear  oogonia;  on  page  297  that  they  are  borne 
on  different  plants.  It  has  been  assumed  that  because  of  mixed  material 
or  from  some  other  cause  his  observations  were  not  correct. 

Fortunately  the  only  species  heretofore  assigned  to  the  genus  has 
strongly  marked  characters  and  Fischer  and  others  have  extended  the 
generic  description  so  as  to  include  a  number  of  the  characters  of  the 
species.  We  are  now  convinced  that  Saprolegnia  Treleaseana  is  co-generic 
with  Aplanes  Braunii  ( A .  androgynus )  and  that  the  genus  should  be  re¬ 
defined  so  as  to  include  it,  as  neither  species  can  be  properly  assigned  to 


APLANES 


77 


any  other  genus.  It  is  also  obvious  that  these  species  are  related  to 
Saprolegnia  hypogyna  and  it  may  in  the  end  be  best  to  transfer  it  also  to 
A  planes.  However,  as  its  sporangia  and  spores  are  well  known  to  be  of  the 
Saprolegnia  type  and  behavior,  so  that  it  may  be  retained  in  that  genus 
without  violence,  we  think  it  best  to  let  it  alone  for  the  present  at  least. 
Saprolegnia  litoralis  is  a  connecting  link  with  the  Ferax  group. 

As  modified  to  include  A.  Treleaseana  the  genus  A  planes  may  be  de¬ 
fined  as  follows  (adapted  in  part  from  Fischer) : 

Mycelium  as  in  Achlya.  Sporangia  extremely  scarce,  often  entirely 
absent  for  long  periods  in  culture,  cylindrical,  renewed  as  in  Saprolegnia 
and  perhaps  also  as  in  Achlya ;  spores  at  times  escaping,  at  times  retained 
in  the  sporangium  and  sprouting  there,  their  behavior  not  well  known. 
Oogonia  abundant,  in  chains  or  single  and  terminal,  barrel-shaped, 
spherical  or  pyriform,  their  walls  very  thick  (more  so  than  in  other  water 
molds)  and  heavily  pitted.  Antheridial  branches  arising  from  imme¬ 
diately  below  the  oogonia,  or  when  the  oogonia  are  in  chains  arising  from 
the  top  of  one  oogonium  and  attached  to  the  next  above,  simple  or 
branched,  the  antheridia  with  their  sides  attached  to  the  oogonia.  Eggs 
centric,  at  times  elliptic  from  pressure. 

1.  Aplanes  androgynus  (Archer)  Humphrey.  Trans.  Am.  Phil.  Soc. 
17:  134.  1892  [1893]. 

Saprolegnia  androgyna  Archer.  Quart.  Jour.  Mic.  Sci.  7  n.  s. :  123, 
pi.  6,  fig.  1.  1867. 

Achlya  Braunii  Reinsch.  Jahrb.  f.  wiss.  Bot.  11:  284,  pi.  14,  figs. 
1-6.  1878. 

Aplanes  Braunii  deBary.  Bot.  Zeit.  46:  650,  pi.  9,  fig.  2.  1888. 

This  has  been  reported  five  times:  by  Archer  from  England,  by 
Petersen  (To,  p.  526)  from  Denmark,  and  by  Reinsch,  deBary  and 
Minden  from  Germany.  It  is  easily  recognized  by  the  very  scarce 
sporangia,  by  the  peculiar  oogonia  which  are  often  in  chains,  their  walls 
thick  and  very  strongly  pitted,  their  shape  subspherical  or  more  often 
spindle-shaped  or  pyriform  or  barrel-shaped,  and  by  the  antheridial 
branches  which  are  slender,  often  branched,  springing  from  immediately 
beneath  each  oogonium  and  pressed  against  it,  with  small  antheridia 
on  their  tips.  Eggs  numerous,  centric,  22-34^.  thick  (Minden).  Oogonia 
about  65-90  X  i20-i60[jl 

Archer  describes  his  plant  thus: 

“Plant  monoecious;  oogonia  large,  barrel-shaped  or  elliptic,  mostly 
in  an  uninterrupted  terminal  series,  though  occasionally  interstitial, 
the  terminal  oogonium  the  oldest  in  a  series,  the  oogonia  thus  showing 
gradually  different  degrees  of  development  down  to  the  basal  one  which 
is  the  youngest;  the  lateral  male  branches,  with  the  exception  of  tho^c 
fertilizing  the  lowest  oogonium  of  a  series,  are  not  derived  either  from 


78 


THE  SAPROLEGNIACEAE 


the  principal  stem  of  the  plant  or  from  any  neighboring  portion  of  the 
general  plant,  but  these  are  given  off  from  the  oogonium  itself,  which 
is  next  immediately  beneath  the  oogonium  which  is  fertilized  by  them, 
and  so  on  down  to  the  lowest  or  basal  oogonium  of  a  series,  to  which 
last  are  given  off  lateral  male  branchlets  from  the  original  filament  or 
stem  immediately  thereunder.  The  tube  or  cavity  of  each  lateral  male 
branchlet  becomes  shut  off  by  a  septum  formed  a  short  distance  above 
its  origin,  the  portion  of  the  contents  above  the  septum  being  developed 
into  the  male  element — that  portion  of  the  contents  below  the  septum 
retaining  its  characters,  and  being  returned  back  into  the  oogonium 
whence  it  originated  in  time  to  become  employed,  with  the  remainder 
of  the  contents,  in  the  formation  of  the  oospores.  Oospores  large,  about 
sio  °f  an  inch  in  diameter,  mostly  numerous,  but  very  variable  in  num¬ 
ber,  sometimes,  though  rarely,  as  few  as  even  one.  They  occasionally 
exhibit  what  appears  to  be  a  roundish  eccentric  vacuole.  The  whole 
plant  large  and  coarse  as  compared  with  other  described  forms  in  this 
family.” 

In  an  introductory  discussion  Archer  states  that  he  saw  no  zoospores 
but  is  led  to  place  the  species  in  Saprolegnia  because  he  once  found  a 
group  of  three  empty  sporangia,  one  within  the  other,  each  with  a  terminal 
opening.  The  one  good  figure  shows  four  barrel-shaped  oogonia  in  a  row, 
the  apical  one  with  a  terminal  papilla.  Thickness  of  wall  or  pits  not  shown. 

Humphrey  points  out  that  Saprolegnia  androgyna  Archer  is  the 
same  in  all  probability  as  Achlya  Braunii  Reinsch  and  as  A  planes  Braunii 
deBary.  DeBary,  with  slight  reservation,  thought  his  plant  the  same 
as  Reinsch’s,  but  overlooked  the  similarity  of  S.  androgyna.  Reinsch 
states  positively  that  sporangia  occur  which  show  cell  nets  after  the 
escape  of  the  spores.  He  also  says  that  in  most  cases  after  the  emergence 
of  the  spores  the  cell  nets  are  not  visible,  indicating  that  they  disappear 
soon.  His  implication  throughout  is  that  the  spores  always  escape  as 
in  Dictyuchus,  and  one  of  his  figures  (fig.  5,  pi.  14)  clearly  shows  this 
method.  However,  in  fig.  2  he  shows  two  sporangia  attached  to  an 
oogonium  which  are  empty  and  show  distinct  openings  for  the  discharge 
of  the  spores.  In  fact  Reinsch  did  not  observe  at  all  the  “  A planes 
type”  of  spore  germination,  as  deBary  later  described  it  (Bot.  Zeit.  46: 
651.  1888).  When  we  remember  that  deBary  speaks  of  the  sporangia 
as  of  great  rarity,  it  seems  to  us  that  we  are  entirely  unjustified  in  as¬ 
serting  that  the  spores  of  A  planes  have  no  swimming  stage.  All  of 
Reinsch’s  testimony,  as  well  as  Archer’s,  is  the  other  way,  and  as  Fischer 
says  (’9 2,  p.  367)  there  can  be  no  doubt  that  Reinsch’s  plant  and  deBary’s 
are  the  same.  In  his  description  of  the  genus  Fischer  admits  that  net 
sporangia  (as  in  Dictyuchus )  seem  also  to  occur  occasionally. 

Minden  finds  a  plant  (1912,  p.  573)  that  he  thinks  is  Achlya  Braunii 
of  Reinsch  ( Aplanes  of  deBary)  and  he  gives  one  figure  of  the  oogonia 


A  PLANES 


79 

(fig.  8,  p.  556)  showing  two  long  oogonia,  one  apical  and  one  intercalary, 
each  with  long  antheridia  wrapped  about  it.  He  found  the  plant  after 
it  was  a  little  old  and  was  not  able  to  follow  the  behavior  of  the  spores, 
but  his  preparations  showed  a  few  sporangia.  These  were  like  those  de¬ 
scribed  by  deBary  with  spores  sprouting  into  threads  from  within  the 
sporangium.  He  did  not  observe  dictiosporangia.  It  may  be,  of  course, 
that  there  are  two  forms  of  this  species  differing  from  each  other  in  the 
behavior  of  the  spores. 

2.  Aplanes  Treleaseanus  (Humphrey)  n.  comb. 

Saprolegnia  Treleaseana  Humphrey.  Trans.  Am.  Phil.  Soc.  17:  111, 
pi.  1 7,  figs.  56-59.  1892  [1893]. 

Saprolegnia  sp.  2  Reinsch.  Jahrb.  f.  wiss.  Bot.  11:  295,  pi.  14,  figs. 
7,  8,  11,  12,  13.  1878. 

Saprolegnia  paradoxa  Petersen.  Bot.  Tidssk.  29:  379.  1909;  also 
Ann.  Myc.  8:  520,  fig.  1  d  and  e.  1910. 

Not  S.  paradoxa  Alaurizio.  Mitt.  d.  Deutsch.  Fischerei-Vereins  7, 
heft  2:  46.  1899. 

Saprolegnia  monoica  var.  turfosa  Minden.  Krypt.  Flora  Mark 
Brandenburg  5:  516.  1912. 

Saprolegnia  turfosa  (Minden)  Gaumann.  Botaniska  Notiser,  1918, 
P-  154- 

Achlya  Treleaseana  (Humph.)  Kauffman.  Ann.  Rept.  Mich.  Acad. 
Sci.  8:  27.  1905. 

Plate  20 

Growdh  moderately  stout,  threads  about  15-25^  thick;  sporangia 
very  scarce,  usually  entirely  absent,  cylindrical,  rounded  at  the  tip, 
proliferating  internally  in  the  few  we  have  seen;  spores  about  ii;ji  in 
diameter.  Gemmae  fairly  plentiful  (not  nearly  so  abundant  as  in  S. 
litoralis),  the  great  majority  rod-shaped  and  in  chains  exactly  as  in  Achlya 
deBaryana ,  only  here  and  there  one  fusiform  or  oval,  etc.  Oogonia 
spherical  (without  a  neck),  or  rarely  oblong  or  pyriform,  smooth  or  at 
times  papillate-warted,  27-90^  in  diameter,  nearly  ahvays  racemosely 
borne  on  short  stalks  (no  intercalary  or  cylindrical  ones  seen) ;  wall 
hyaline,  varying  in  thickness  with  the  size  of  the  oogonia;  in  small  ones 
as  little  as  i.2[j.  thick,  in  large  ones  thicker  than  in  any  species  of  Sapro¬ 
legnia  or  A  chlya,  and  reaching  up  to  4[jl  ;  pits  numerous  and  very  conspicuous 
(few  and  less  conspicuous  in  small  oogonia).  Eggs  1-30,  mostly  6-20  in 
an  oogonium,  2a-26[j.  thick,  often  elliptic  or  block-shaped  from  pressure, 
and  usually  well  filling  or  even  crowding  the  oogonium,  centric;  vrall 
thick.  Antheridia  on  all  the  oogonia,  very  peculiar,  arising  from  short 
stalks  which  spring  laterally  from  immediately  beneath  the  oogonia,  an 
antheridial  cell  not  being  cut  off  from  the  oogonial  stalk  except  in  very 
few  cases;  tubes  from  the  partition  wrall  into  the  oogonium  lacking.  I  he 
whole  of  the  antheridial  thread  may  be  cut  off  as  an  antheridium  or  only 
a  part  of  it;  at  times  also  no  w7all  cutting  off  an  antheridium  can  be  seen. 


8o 


THE  SAPROLEGXIACEAE 


Found  by  us  twice,  first  near  Southport,  N.  C.,  in  a  ditch  with  algae? 
April  6,  1918;  again  from  a  little  pond  near  Trenton,  N.  C.,  February  24, 
1922  (Mrs.  Matherly,  coll.).  Reported  from  Michigan  by  Kauffman  (l.c.). 

Humphrey  described  his  species  from  Trelease’s  notes  and  ma¬ 
terial  and  never  saw  the  living  plant.  He  describes  the  oogonia  as 
having  rather  scattered  blunt  outgrowths  and  no  pits.  Our  plant  has 
such  outgrowths  on  only  a  part  of  the  oogonia  and  very  conspicuous 
pits,  but  these  apparent  discrepancies  do  not  weigh  very  heavily  with  us, 
as  Humphrey’s  material  was  probably  scanty  and  the  pits  do  not  appear 
in  areas  where  the  projections  are  moderately  frequent.  The  positive 
characters  are  too  convincing  for  us  to  doubt  the  identity  of  the  two 
plants. 

This  species  has  had  a  curious  history.  It  is  certainly  the  same  as 
S.  monoica  var.  turfosa  of  Minden,  which  he  later  (Krypt.  FI.  Mark  B.  5: 
608.  1912)  recognizes  as  the  previously  described  species  S.  paradoxa 
Petersen,  and  admits  to  be  of  good  specific  rank.  This  name  cannot  stand, 
however,  as  it  had  been  used  for  a  different  plant  ten  years  earlier  by 
Maurizio,  a  fact  overlooked  by  Minden.  Minden ’s  description  fits  our 
plant  perfectly  except  that  he  says  the  oogonial  walls  are  yellowish  and 
does  not  mention  the  scarcity  of  sporangia.  Petersen  says  of  his  species 
that  the  oogonial  walls  are  dilute  yellow  to  hyaline.  Minden  also  refers  to 
Reinsch’s  unnamed  “Sap.  No.  2”  as  being  the  same,  evidently,  as  shown 
from  the  latter’s  good  figures  (a  fact  that  we  had  also  noted  for  our  plant 
before  seeing  Minden ’s  work).  Two  of  Reinsch’s  figs,  show  cylindrical 
oogonia,  a  condition  not  recorded  by  others.  (See  note  under  S',  anisospora 
on  the  parasite  shown  in  Reinsch’s  fig.  n).  Gaumann  finds  the  species  in 
Lapland  and  calls  it  S.  turfosa.  It  is  significant  that  both  Reinsch  and 
Minden  found  the  present  species  associated  with  A  planes  androgynus. 

The  plant  is  near  S.  hypogyna  but  is  sharply  marked  by  its  very  thick 
oogonial  wall,  racemosely  borne  oogonia  on  short  stalks,  and  by  the 
peculiar  origin  of  the  antheridial  branches,  resembling  in  the  latter  respect 
A  planes  androgynus  and  at  times  even  Pythiopsis  cymosa.  A  similar 
origin  of  these  branches  is  also  found  at  times  in  Forms  3  and  8  of  A. 
hypogyna ,  but  they  differ  easily  in  the  hypogynous  cell,  in  thinner  walls, 
etc.  Kauffman  gives  the  sporangia  as  abundant  in  his  form  (Form  8) 
of  S.  hypogyna. 

Petersen  says  of  his  plant  that  the  walls  of  the  hyphae  are  very  thick, 
and  suggests  that  this  may  be  due  to  a  parasite.  Minden  does  not  mention 
this  in  his  first  description  of  A.  monoica  var.  turfosa ,  but  later  (p.  608) 
he  notes  that  the  hyphae  (walls  ?)  are  thick  and  yellow,  and  the  ends  are 
often  splintered.  This  last  peculiarity  must  refer  to  old,  dead  hyphae. 
The  hyphal  walls  in  our  plant  are  not  particularly  thick,  so  far  as  they 


PLATE  20 


PLATE  20 

Aplanes  Treleaseanus 

Fig.  i.  Gemmae.  X  503. 

Fig.  2.  Proliferating  sporangia.  X  278. 

Fig.  3.  Sporangia  in  basipetal  arrangement.  X  278. 

Fig.  4.  Gemmae.  X  278. 

Fig.  5.  Oogonium  with  a  single  ripe  egg.  X  503. 

Fig.  6.  Oogonia  with  large  papillae.  X  503. 

Fig.  7.  Gemmae  in  basipetal  arrangement.  X  278 

Fig.  8.  Empty  oogonium  (optical  section  and  surface  view  combined).  X  503. 
Fig.  9.  Oogonium  with  a  single  papilla.  X  503. 

Fig.  10.  Irregularly  shaped  oogonium  with  ripe  eggs.  X  503. 

Figs.  II,  12  and  13.  Various  forms  of  oogonia  and  antheridia.  All  X  503. 


PLATE  20 


APLANES  TRELEASEANUS, 


ISOACHLYA 


8l 


have  appeared  in  our  cultures,  and  we  are  inclined  to  think  that  such 
hyphae,  with  such  thick  walls,  are  only  occasional  in  the  European  plants. 
They  are  not  shown  or  mentioned  by  Reinsch. 

The  sporangia  and  spores  of  this  species  are  scarcely  better  known 
or  more  consistently  described  than  in  A.  androgynus.  Humphrey  saw 
no  sporangia,  but  placed  the  species  in  Saprolegnia  because  Trelease  saw 
one  sporangium  which  he  said  was  like  those  of  Saprolegnia  and  which 
he  drew  empty  with  an  open  tip  (Humphrey,  ’92,  pi.  17,  fig.  56).  Reinsch 
(pi.  14)  gives  three  figures  showing  external  proliferation  through  empty 
sporangia,  but  gives  no  detail  as  to  the  behavior  of  the  spores.  Petersen 
(To,  p.  520)  refers  his  plant  to  Saprolegnia  with  much  doubt  and  solely 
on  the  proliferation  of  the  sporangia.  He  does  not  mention  the  spores  or 
their  behavior,  a  fact  which  indicates  that  the  sporangia  were  rare. 
Minden  (l.c.)  does  not  mention  the  sporangia  and  spores  in  the  body  of 
his  description  of  his  var.  turfosa,  but  says  the  plant  cannot  be  Achlya 
racemosa  because  of  the  method  of  spore  escape  and  the  long,  internally 
proliferating  sporangia.  Kauffman  (’05,  p.  27)  finds  the  species  in 
Michigan  and  transfers  it  to  Achlya  as  “the  sporangia  emptied  in  the 
manner  of  Achlya;  in  every  other  respect  it  agreed  with  Saprolegnia 
Treleaseana  Humphrey,  and  is  no  doubt  the  same  plant.” 

As  to  ourselves,  we  can  add  little  to  clear  up  the  uncertainty.  The 
very  few  sporangia  we  have  seen  looked  like  those  of  Saprolegnia  and  had 
emptied  at  the  tip  and  proliferated  internally(figs.  2  and  3 ;  emptied  gemmae 
are  also  shown).  We  have  not  seen  the  spores  emerge.  Our  experience 
emphasizes  the  very  great  rarity  of  the  sporangia.  The  ones  shown  were 
from  our  first  collection  (1918)  which  was  unfortunately  lost  during 
the  summer  vacation.  The  other  collection  (1922)  yielded  not  a  single 
sporangium,  although  cultivated  for  about  three  months  on  many  sorts 
of  media  and  in  different  temperatures  with  this  object  in  view.  Media 
used  were  flies,  termites,  mushroom  grubs,  corn  grain,  beans,  etc. 

ISOACHLYA  Kauffman,  1921,  p.  231. 

Hyphae  rather  stout  or  slender.  Zoosporangia  formed  from  their 
tips,  oval,  pyriform,  ventricose-clavate,  elongated  pyriform  to  clavate 
or  cylindrical-clavate;  the  later  ones  (secondary)  arising  either  by 
cymose  or  pseudo-cymose  arrangement,  as  in  Achlya,  or  by  internal  pro¬ 
liferation  as  in  Saprolegnia,  both  modes  occurring  earlier  or  later  in  the 
development  of  one  and  the  same  species,  or  frequently  on  the  same  main 
hypha.  Zoospores  diplanetic,  as  in  Saprolegnia,  escaping  and  swarm¬ 
ing  separately,  and  after  encystment  swarming  the  second  time  before 
the  formation  of  a  germ-tube.  Oogonia  terminal  or  torulose,  occa¬ 
sionally  intercalary.  Oospores  with  centric  or  eccentric  contents,  the  spores 
filling  the  oogonium  incompletely.  Antheridia  present  or  few  to  none. 


82 


THE  SAPROLEGN I ACEAE 


The  genus  is  characterized  and  distinguished,  in  the  main,  by  the 
presence  of  the  cymose  or  Achlya  mode  of  formation  of  secondary  spor¬ 
angia,  coupled  with  diplanetic  zoospores. 

The  above  is  copied  without  change  from  the  original  description 
except  for  the  addition  of  the  words  “or  eccentric”  in  speaking  of  the 
oospores,  so  as  to  admit  our  new  species,  7.  eccentrica.  It  should  also 
be  added  that  the  genus  is  characterized  by  the  great  scarcity  of  an- 
theridia,  which  are  absent  in  three  of  the  species  and  few  in  the  other  one. 
In  his  new  genus  Kauffman  proposed  to  include  7.  toruloides,  our  Achlya 
paradoxa  and  Saprolegnia  monilifera.  After  looking  over  the  matter 
carefully  we  have  concluded  that  while  I.  toruloides  and  S.  monilifera 
should  be  put  here,  together  with  our  two  new  species,  7.  unispora  and 
7.  eccentrica,  it  would  not  be  well  to  add  to  them  A.  paradoxa,  which 
differs  materially.  For  the  latter  we  propose  the  genus  Protoachlya.  It 
is  quite  possible  that  other  species  of  Saprolegnia,  such  as  A.  curvata , 
S.  torulosa,  S.  rhaetica,  S.  variabilis  and  5.  bodanicci,  might  be  referred 
to  Isoachlya  if  better  known. 


Key  to  the  Species 

Antheridia  present  on  some  (less  than  half)  of  the  oogonia . 7.  toruloides  (i) 

Antheridia  absent 

Eggs  usually  1-2  in  an  oogonium,  centric . 7.  unispora  (2) 

Eggs  usually  1—2  in  an  oogonium,  eccentric . 7.  eccentrica  (3) 

Eggs  usually  2-6,  centric . 7.  monilifera  (4) 


1.  Isoachlya  toruloides  Kauffman  and  Coker.  Am.  Journ.  Bot.  8: 

231,  pis.  13  and  14.  1921. 

Plate  21 

Threads  delicate  but  vigorous,  moderately  branched,  thickened 
towards  the  sporangia,  reaching  a  length  of  about  6-8  mm.  on  a  mush¬ 
room  grub.  Sporangia  nearly  cylindric  to  clavate  or  irregular,  pro¬ 
liferating  from  within,  or  less  often  laterally  as  in  Achlya,  usually  broad¬ 
est  near  the  papillate  tip,  moderately  abundant  throughout  the  growth 
of  the  culture.  Spores  diplanetic,  1 1.5-12.5^  in  diameter  during  the  first 
resting  stage,  at  times  sprouting  through  the  wall  of  the  sporangium 
as  in  Aplanes  (net-sporangia  not  seen).  Oogonia  abundant,  mostly 
spherical,  not  rarely  oval  or  pyriform  even  though  apical,  at  times  pointed 
or  otherwise  irregular  and  rarely  cylindrical  in  empty  sporangia;  with 
or  without  a  neck;  in  young  cultures  mostly  borne  singly  at  the  tips  of 
main  hyphae,  later  appearing  throughout  the  culture  on  bent  or  crooked 
lateral  branches  about  1-3  times  the  length  of  their  diameter,  these  stalks 
often  sending  out  near  the  oogonium  a  lateral  branch  which  bears  an¬ 
other  oogonium  on  its  tip;  in  older  cultures  often  intercalary  (single)  or 
two  or  three  in  a  row  (moniliform) ;  at  times  a  good  many  may  be  borne 
singly  just  outside  the  mouth  of  empty  sporangia  by  the  through  growth 
of  the  threads  that  bear  them;  walls  thin,  about  1.34  thick,  colorless, 


PLATE  21 


PLATE  21 


ISOACHLYA  TORULOIDES 

Fig.  I.  Gemmae.  X  167. 

Fig.  2.  Oogonia  with  and  without  antheridia.  X  167. 

Fig.  3.  Oogonia  and  gemmae.  X  167. 

Fig.  4.  Oogonia.  X  167. 

Fig.  5.  Proliferation  through  old  sporangia.  X  250. 

Fig.  6.  Oogonia  with  ripe  eggs.  X  417. 

Fig.  7.  Oogonia  in  chain  with  an  old  sporangium  on  tip  of  chain.  X  1E7 
Fig.  8.  Oogonium.  X  250. 

Fig.  9.  Gemmae,  sporangia,  and  an  oogonium  on  same  hypha.  X  167. 

Fig.  10.  Oogonia  in  a  chain.  X  250. 

Fig.  11.  A  group  of  sporangia  of  Aclilya-Wke  origin,  one  showing  internal  proliferation. 

Fig.  12.  A  spherical  oogonium  and  a  cylindrical  oogonium  in  old  sporangium  on  same 
hypha.  X  250. 

Fig.  13.  Oogonia,  one  with  a  antheridium.  X  417. 


Lv; 


PLATE  21 


ISOACHLYA  TORULOIDES. 


ISOACHLYA 


83 


with  a  few,  usually  1  or  2,  inconspicuous  pits,  or  often  with  no  pits  visible. 
Antheridial  branches  diclinous,  usually  'ateral  from  small  threads  in 
the  neighborhood  of  oogonia,  sometimes  from  branches  which  bear 
oogonia,  very  clear  and  hyaline,  delicate,  quickly  disappearing  after 
the  formation  of  the  antheridia;  antheridia  absent  on  most  of  the  first 
oogonia,  present  on  a  varying  proportion  of  the  later  ones,  usually  few, 
varying  from  almost  none  (less  than  jG  of  1%)  to  about  10%  or  15% 
or  even  45%  on  grubs,  cylindrical  or  tuberous,  laterally  applied  and 
partly  embracing  the  oogonia,  not  wrapping  them  about,  easily  visible 
after  their  threads  disappear;  antheridial  tubes  formed.  Eggs  usually 
1-6,  rarely  8  or  12,  centric,  very  variable  in  size,  1  i~33;j.  in  diameter, 
most  about  22-30(0.,  extremes  often  mixed  in  the  same  oogonium.  Gem¬ 
mae  not  very  abundant,  sub-spherical  or  pyriform  or  irregularly  rod¬ 
shaped,  often  in  moniliform  chains. 

Rare;  found  in  Chapel  Hill  only  four  times:  in  the  marsh  opposite 
the  cemetery,  January  12,  1917,  and  again  on  April  30,  1918;  in  the 
branch  at  west  end  of  Battle’s  Park,  February  2,  1918;  and  among 
decaying  leaves  in  a  little  branch  behind  Dr.  Archibald  Henderson’s 
house,  March  8,  1918. 

Kauffman  found  his  plant  at  Ann  Arbor,  Mich.,  November  23,  1920, 
in  shallow  water  over  peat-like  organic  remains,  shore  of  First  Sister 
Lake  and  in  a  pool  of  sphagnum  near  by.  He  read  a  diagnosis  of  his 
plant  as  a  species  under  Isoachlya,  but  without  specific  name,  before  the 
Botanical  Society  of  America,  and  I  found  on  receiving  the  manuscript 
from  him  that  his  plant  and  mine  were  the  same  with  perhaps  a  varietal 
difference.  We  then  decided  to  publish  this  jointly.  The  diagnosis  as 
given  above  by  me  is  from  the  Chapel  Hill  form.  It  will  be  noted  that 
the  two  forms  differ  in  no  important  respect  except  in  the  maximum 
number  and  size  of  the  eggs  in  the  Chapel  Hill  form. 

This  is  easily  distinct  from  our  other  North  Carolina  species,  and 
outside  of  its  own  genus  seems  nearest  S.  torulosa,  as  described  by  de- 
Bary  and  by  Fischer.  It  differs  from  the  latter  in  the  much  smaller 
proportion  of  chained  to  single  oogonia,  in  the  antheridia  being  only 
diclinous  and  apparently  more  numerous,  and  in  the  larger  average  size 
of  the  eggs.  In  3.  torulosa  the  oogonia  are  said  to  be  almost  always  in 
torulose  rows,  while  in  our  plant  the  single  ones  are  far  more  common. 
Humphrey  says  of  the  oogonia  “commonly  in  torulose  series,’’  but  of 
two  slides  of  his  labelled  S.  torulosa  one  shows  only  a  few  such  rows, 
most  of  the  oogonia  being  single  as  in  our  plant,  and  with  a  good  many 
antheridia,  while  the  other  looks  more  like  I.  monilifera,  with  brown- 
walled  oogonia  in  chains  that  are  separating  from  each  other.  1  he 
first  mentioned  slide  may  be  the  present  species  but  the  oogonia  have 
many  more  pits,  and  its  identity  is  doubtful.  It  is  probable  that  on 


84 


THE  SAPROLEGNIACEAE 


more  careful  study  S.  torulosa  will  be  found  to  belong  to  this  genus. 
See  S.  rhaetica  and  A.  variabilis  which  are  also  near. 

In  the  character  and  extent  of  its  mycelium  and  in  some  other  char¬ 
acters  also  this  species  is  most  like  S.  delica.  The  few  and  always  di¬ 
clinous  antheridia  are  the  most  striking  character  distinguishing  this 
from  S.  delica.  Another  difference  is  the  more  hyaline  and  more  quickly 
disappearing  antheridial  branches,  which  are  more  difficult  to  trace  than 
in  S',  delica  and  S.  anisospora.  Moreover,  the  antheridia  when  present 
are  rarely  over  one  or  two  and  are  never  numerous  enough  to  cover  or 
almost  cover  the  oogonium,  as  is  so  often  the  case  in  S.  delica  and  S. 
anisospora.  Nearly  all  the  antheridia  are  found  in  the  denser,  central  part 
of  the  culture,  the  long  and  conspicuous  antheridial  branches, winding 
about  the  periphery  in  S.  delica ,  being  absent.  Another  difference  from 
the  latter  is  found  in  the  frequent  appearance  of  oogonia  on  short  branches 
from  just  below  the  terminal  ones,  and  also  in  the  rather  constant  ap¬ 
pearance  of  a  number  of  oval  or  pointed  or  otherwise  irregular  oogonia 
in  each  culture.  From  S.  diclina  it  is  easily  separated  by  the  few  an¬ 
theridia,  fewer  eggs  and  much  less  abundant  gemmae.  From  A.  ferax, 
which  may  have  about  the  same  proportion  of  antheridia,  it  differs  in 
having  smaller  oogonia,  with  fewer  and  far  less  conspicuous  pits,  much 
fewer  cylindrical  oogonia,  diclinous  antheridia  and  fewer  eggs.  In  the 
same  way  it  differs  from  S.  mixta,  if  that  is  a  good  species. 

The  oogonia  have  a  pitted  appearance  when  the  protoplasm  is  pre¬ 
paring  to  divide,  just  as  in  many  other  species.  These  spots  are  ap¬ 
parently  oil  drops  or  vacuoles  just  below  a  surface  layer  of  protoplasm, 
and  have  no  correspondence  to  the  real  pits  that  appear  later. 

At  temperature  of  790  F.  the  spores  are  expelled  with  force  in  a 
semitorpid  state,  gather  strength  after  a  few  seconds  of  slow  movement 
in  an  open  cluster  and  then  swim  off.  They  are  popped  out  with  vio¬ 
lence  a  distance  of  one-fourth  to  one-half  the  length  of  the  sporangium, 
although  almost  dormant — a  sure  evidence  of  internal  pressure  being  the 
cause  of  emergence. 

The  following  cultures  were  made  from  No.  8  of  March  8,  1918: 

In  .05%  haemoglobin  solution  on  house  fly  the  growth  was  only  fairly  vigorous.  Many 
oogonia,  but  few  antheridia.  Few  sporangia.  The  oogonia  initials  form  readily 
enough  in  haemoglobin  solution,  but  the  eggs  do  not  round  up  until  the  growth  is 
transferred  to  pure  water. 

In  equal  parts  of  .05%  haemoglobin  solution  and  .25%  NaH2P04  on  fly.  Growth  quite 
vigorous,  more  so  than  in  any  other  of  the  solutions  tried,  many  oogonia  formed  and 
many  antheridial  branches,  but  few,  in  comparison  to  the  ones  formed,  were  applied 
to  oogonia.  A  good  many  empty  sporangia  seen.  As  in  above  experiment  no  eggs 
were  formed  until  culture  was  transferred  to  pure  water. 


ISOACHLYA 


85 


In  equal  parts  of  .05%  haemoglobin  solution,  .25%  NaH2P04,  and  .25%  K3P04  on  fly. 
Growth  slender,  a  fair  number  of  oogonial  initials,  few  antheridia.  Upon  transferring 
the  culture  to  pure  water  many  sporangia  were  formed,  and  a  good  many  oogonia  with 
eggs  and  with  antheridia  attached  to  them. 

In  equal  parts  of  .05%  haemoglobin,  .25%  NaH2P04,  .25%  K3P04,  and  .25%  Ca3(P04)t, 
growth  vigorous,  many  oogonia  (but  few  with  eggs)  and  many  antheridial  branches, 
but  only  a  few  applied  to  oogonia.  In  this  culture  many  hyphae  gave  rise  to  numerous 
antheridial  branches  all  along  the  hypha  from  the  base  almost  to  the  tip.  Many  of 
these  resembled  branched  and  tortuous  root  hairs.  The  culture  transferred  to  pure 
water  and  left  standing  for  a  few  days  and  then  examined.  It  contained  many  oogonia 
with  eggs  and  many  empty  sporangia  and  gemmae.  The  antheridial  branches  had 
disappeared. 

On  piece  of  boiled  corn  grain  cut  from  the  germ  but  also  having  some  of  the  hard  and  soft 
endosperm  of  grain.  Growth  vigorous,  sporangia  produced  in  fair  number  during 
youth  of  culture  and  all  of  them  emptying.  Oogonia  produced  in  great  abundance, 
varying  much  in  size  and  shape  and  in  the  number  of  eggs.  Antheridia  very  scarce, 
only  2  oogonia  with  antheridia  having  been  seen  in  the  whole  culture.  In  cases 
where  antheridia  were  seen  antheridial  tubes  were  developed. 

On  piece  of  boiled  corn  grain  cut  from  the  germ.  Growth  vigorous,  a  fair  number  of  spor¬ 
angia  present.  Oogonia  produced  in  great  abundance,  varying  considerably  in  shape 
from  spherical  to  cylindrical.  Antheridia  almost  totally  absent,  only  one  oogonium 
with  antheridium  having  been  seen. 

On  corn  meal  agar,  growth  fairly  rapid,  vigorous,  covering  the  agar  in  petri  dish  in  about 
two  days.  No  sporangia.  Oogonia  produced  in  great  abundance,  a  large  majority 
of  them  containing  perfectly  formed  eggs.  About  5%  of  oogonia  with  antheridia. 
Some  of  the  oogonia  very  irregular  in  shape. 

2.  Isoachlya  unispora  Coker  &  Couch  n.  sp. 

Plates  22  and  23 

Mycelium  vigorous,  more  extensive  than  in  most  species  of  Sapro- 
legnia;  hyphae  irregular,  not  straight  or  cylindrical,  normally  little 
branched,  about  10-35:0.  thick,  and  usually  largest  toward  the  periphery; 
sporangia  typically  scarce,  frequently  almost  none,  often  quite  irregular; 
primary  ones  elongated,  varying  from  sub-cylindrical  and  slightly  if  at 
all  thicker  than  the  hyphae  to  shorter,  thicker,  and  more  flask-shaped; 
secondary  sporangia  arising  by  cymose  branching,  and  also  not  rarely 
growing  through  the  empty  ones,  but  in  such  cases  the  new  sporangia 
forming  entirely  outside  the  mouth  of  the  old  ones;  spores  diplanetic, 
9.3— 1 3.7P.,  most  about  10.5-11.5^.  thick  at  rest;  emptying  as  in  Sapro- 
legnia  and  swimming  rather  sluggishly  and  aimlessly,  some  coming 
quickly  to  rest:  on  emerging  from  the  cysts  they  swim  longer  and  more 
actively.  Not  rarely  the  spores  remain  in  the  sporangia  and  sprout 
there  as  in  most  other  species  at  times.  Gemmae  plentiful  or  few, 
typically  spherical,  with  or  without  a  neck,  usually  in  chains,  the  distal 
member  of  which  is  not  rarely  an  oogonium;  emptying  on  changed  con¬ 
ditions  by  an  elongated  papilla.  Oogonia  abundant,  mostly  spherical, 
rarely  pyriform,  usually  with  a  distinct  neck  and  borne  on  lateral  branches, 
quite  often  terminal  on  small  hyphae,  and  in  strong  cultures  frequently 
in  clusters,  with  the  arrangement  of  a  scorpioid  cyme,  not  rarely  inter- 


86 


THE  SAPROLEGNIACEAE 


calary  or  in  chains  of  two  or  three,  sometimes  cylindrical  inside  old 
sporangia;  diameter  24-75^,  most  about  50;a,  wall  clear  at  first,  dis¬ 
tinctly  yellowish  in  age,  about  2.8^.  thick,  with  few  (usually  2  or  3  visible) 
very  large  and  conspicuous  pits.  Eggs  few,  usually  one,  often  two, 
rarely  three  and  very  rarely  four,  18.5-43^  in  diameter,  most  about 
32-35^  when  two  in  one  oogonium  or  40-45^  when  only  one;  centric. 
Antheridia  never  developed. 

Found  four  times  by  Mr.  J.  N.  Couch,  April  25,  1918,  and  June  22, 
1918,  in  a  drinking  trough  for  horses  about  2jJ  miles  east  of  Chapel 
Hill;  and  April  30,  1918,  and  February  18,  1921,  in  the  marshy 
place  opposite  cemetery  in  Battle’s  Park. 

Differs  from  I.  toruloides  in  larger  and  fewer  eggs,  more  scorpioid 
arrangement  of  oogonia  at  times,  and  absence  of  antheridia.  This 
peculiar  species  has  a  decided  resemblance  to  Pythiopsis  Ilumphrey- 
ana  in  its  few  large  eggs,  appearance  of  the  oogonia,  cymose  branch¬ 
ing,  etc.,  but  the  latter,  as  well  as  P.  cymosa,  has  monoplanetic  spores. 
There  is  a  tendency,  though  not  a  strong  one,  for  the  oogonia  when  in 
chains  to  become  separated  from  each  other;  in  this  respect,  as  well  as 
in  the  yellowish  walls,  approaching  S.  monilifera.  There  are  formed  not 
rarely  at  the  base  of  the  oogonia  ingrowing  tubes  through  the 
partition  wall.  These  usually  reach  the  egg  and  may  indeed  run  along 
the  egg  surface  and  approach  the  distal  side  of  the  oogonium.  Such  tubes 
do  not  seem  to  be  in  any  sense  antheridia,  as  they  not  only  do  not  discharge 
but  become  thick-walled  and  often  nodulated.  In  an  ordinary  culture 
in  distilled  water  spores  were  seen  to  emerge  at  10:04  A.  M.,  and  swim  slug¬ 
gishly  and  aimlessly;  some  came  to  rest  in  less  than  a  minute,  all  in  about  30 
minutes,  at  temperature  of  86°  F.  A  similar  observation  was  made  on 
another  collection  about  three  years  later.  Spores  swam  from  one-half 
minute  to  thirty  minutes,  most  coming  to  rest  after  twenty  minutes. 
It  is  remarkable  that  after  repeated  renewal  of  cultures  in  the  laboratory 
the  color  in  the  oogonial  walls  tends  to  disappear.  This  is  true  also  of 
Achlya  color ata. 

Maurizio  described  a  new  species,  Saprolegnia  bodanica ,  which  is 
apparently  in  the  same  group  as  S.  monilifera,  and  5.  torulosa.  S.  bo¬ 
danica  has  no  antheridia  and  has  a  somewhat  irregular  habit  of  growth. 
In  these  two  ways  it  is  similar  to  Isoachlya  unispora.  But  the  two 
species  are  distinct  in  that  the  latter  never  has  over  4  eggs  in  an  oogo¬ 
nium,  and  usually  has  only  one,  while  none  of  Maurizio’s  figures  show 
an  oogonium  with  one  egg,  and  most  of  them  have  over  four;  the  oogonia 
in  Isoachlya  unispora  have  from  one  to  several  (usually  2  or  3)  large 
pits,  while  the  oogonia  of  S.  bodanica  have  (in  Maurizio’s  figures)  9-1 1 
pits. 


PLATE  22 


PLATE  22 

ISOACHI.YA  UNISPORA 

Fig.  i.  Oogonium  in  an  old  sporangium.  X  278. 

Figs.  2-6.  Various  forms  of  sporangia  and  proliferation.  3,  5  and  6  X  278;  2  and  4  X 
188. 

Fig.  7.  Proliferation  as  in  Saprolegnia.  X  278. 

Fig.  8.  Proliferation  through  old  sporangial  wall.  X  278. 

Fig.  9.  a  Two  spores  stained  upon  emerging  to  show  cilia;  b  two  double  spores  with  4  cilia 
and  one  double  spore  encysted;  c  three  encysted  spores  and  one  emerging 
from  cyst;  d  and  e  masses  of  protoplasm  escaped  from  sporangium  without 
forming  into  spores.  All  X  810. 

Fig.  10.  Gemmae  in  a  chain  with  an  oogonium  at  tip  of  chain.  X  278. 

Fig.  11.  Sporangia  renewed  as  in  Achlya.  X  278. 

Fig.  12.  Sporangia  renewed  as  in  Pythium.  X  278. 

Fig.  13.  Sporangia  renewed  as  in  Achlya  and  in  Pythium.  Culture  on  corn  meal  agar 
square  in  FLO.  X  278. 

Fig.  14.  Showing  hypha  growing  through  wall  and  forming  sporangium  as  in  8.  On  corn 
meal  agar  square  in  distilled  FLO.  X  278. 


PLATE  22 


ISOACHLYA  UNISPORA 


PLATE  23 


PLATE  23 

ISOACHLYA  UNISPORA 

Fig.  I.  Intercalary  and  apical  oogonia.  X  188. 

Figs.  2  and  3.  Typical  clusters  of  oogonia.  X  188. 

Fig.  4.  Habit  of  oogonia.  X  188. 

Fig.  5.  Habit  of  oogonia  showing  some  in  a  chain.  X  188. 

Fig.  6.  Oogonium  with  sporangium  formed  in  part  of  hypha  just  beneath  it. 
Fig.  7.  Irregular  shaped  oogonium.  X  281. 

Fig.  8.  Three  oogonia  in  form  of  a  cross.  X  281. 

Fig.  9.  Oogonia  in  a  chain,  the  one  at  base  empty.  X  281. 

Fig.  10.  Oogonium  in  a  chain  with  gemmae.  X  281. 

Fig.  11.  Oogonium  with  basal  ingrowth.  X  281. 

Fig.  12.  Two  ripe  eggs,  showing  structure.  X  503. 


X  281. 


PLATE  23 


ISOACHLYA  UNISPORA 


ISOACHLYA 


87 


Cultures  of  No.  1  of  April  25,  1918: 

On  pieces  of  boiled  corn  grain  (repeated  several  times) :  Growth  fairly  vigorous  to  very 
vigorous — over  a  centimeter  in  length;  hyphae  somewhat  wavy  and  curled;  sporangia 
produced  normally  as  on  grubs;  many  oogonia  with  eggs  formed. 

On  grubs  in  pure  water  in  ice  box:  Invariably  produced  many  sporangia  and  spores. 
Check  cultures  were  kept  going  out  in  the  laboratory  and  though  the  room  was  quite 
hot  (30°  C.)  they  were  very  vigorous.  They  produced  no  sporangia,  however. 

On  corn  meal  agar:  Growth  fairly  vigorous;  sporangia  present;  many  oogonia  with  eggs; 
no  bacteria  visibly  present.  Same  result  with  No.  1  of  June  22,  1918. 


3.  Isoachlya  eccentrica  n.  sp. 

Plate  24 

Threads  long,  slender,  little  branched,  6-18.54  thick,  most  about 
12-154,  growth  vigorous  on  termite  ants,  bits  of  boiled  corn  grain  and  on 
agar  plates;  length  on  corn  grain  up  to  8mm.,  on  a  termite  ant  up  to  4mm. 
tips  pointed  and  clear.  On  corn  grain  many  or  most  of  the  tips  become 
sporangia  of  a  regular  cylindrical  shape,  with  a  distinct  papilla,  30-45  x 
142-4004,  at  times  broader  in  the  middle,  again  near  the  tips.  On  termite 
ants  the  sporangia  are  less  regular,  with  several  apertures  in  most  cases. 
Proliferation  of  sporangia  not  common,  when  present  never  internal  as 
in  Saprolegnia,  but  irregularly  from  below,  as  in  Achlya  and  Pythiopsis. 
Dictiosporangia  observed  a  few  times.  Spores  diplanetic,  10-114  thick 
when  at  rest,  emerging  rather  slowly  with  the  cilia  directed  backward, 
then  reversing  and  swimming  sluggishly  for  a  very  short  time,  many 
coming  to  rest  in  the  immediate  neighborhood  of  the  sporangium; 
shape  and  contents  as  in  Saprolegnia.  Gemmae  plentiful,  following  the 
sporangia,  very  irregular  in  size  and  shape,  after  a  time  forming  spores. 
Oogonia  spherical  as  a  rule,  seldom  oval,  15-404,  most  about  30-354  thick, 
usually  single,  at  times  in  chains  of  four  or  five;  commonly  borne  on 
short  lateral  stalks  which  are  from  one-half  to  twice  as  long  as  the  diameter 
of  the  oogonia;  often  as  well  on  the  tips  of  threads  which  have  proliferated 
through  empty  sporangia,  and  in  such  cases  not  rarely  formed  inside 
the  sporangia;  sections  of  old  threads  may  also  become  oogonia.  Wall 
colorless,  smooth,  many  without  pits,  some  with  a  few  large,  conspicuous 
ones.  Eggs  usually  one,  often  two,  rarely  three  or  four;  12-31 4  thick, 
most  about  20-254,  eccentric,  with  a  single  large  oil  drop  at  maturity. 
Antheridia  none. 

Found  but  once,  without  intermixture  of  other  forms,  in  a  small 
shallow  pool  with  decaying  leaves,  behind  the  power  house,  Chapel  Hill, 
N.  C.,  December  2,  1921  (F.  A.  Grant,  coll.). 

The  present  plant  is  remarkable  as  being  the  only  species  of  the  family 
with  a  typically  eccentric  egg,  in  which  the  spores  swim  away  on  emerging 
(see  remarks  under  Saprolegnia  anisospora).  Except  for  the  eccentric 
egg  all  other  characters  are  those  of  Isoachlya  and  we  therefore  refer  it 
to  that  genus.  The  nearest  relative  seems  to  be  I.  unispora  which  easily 


88 


THE  SAPROLEGNIACEAE 


differs  in  the  smaller  oogonia  and  smaller,  centric  eggs,  as  well  as  in  other 
less  conspicuous  characters.  It  will  be  noted  that  this  species  as  well 
as  I.  unispora  differs  from  Achlya  not  only  in  the  motility  of  the  primary 
spores,  but  also  in  the  frequent  extension  of  threads  through  empty 
sporangia,  although  this  does  not  lead  to  the  formation  of  nested  sporangia. 

4.  Isoachlya  monilifera  (deBary)  Kauffman.  Am.  Journ.  Bot.  8:  231. 

1921. 

Saprolegnia  monilifera  deB.  Bot.  Zeit.  46:629,  pi.  9,  fig.  6.  1888. 

Plates  25  and  50 

Vegetative  growth  short;  main  hyphae  13-22^  in  diameter  near  base. 
Sporangia  scarce,  often  entirely  absent,  short  or  moderately  long,  usually 
largest  near  the  tip ;  in  older  cultures  the  sporangia  often  proliferating  later¬ 
ally  below  as  in  A chlya.  Spores  1 1-1  i.8[a  in  diameter.  Oogonia  abundantly 
produced  in  a  very  dense  zone  immediately  surrounding  the  substratum, 
appearing  before  the  sporangia,  mostly  in  chains,  the  lower  elements 
of  the  chain  usually  smaller  and  sometimes  remaining  as  gemmae,  com¬ 
monly  spherical  with  or  without  a  basal  neck,  rarely  elongated  inside 
old  sporangia  (in  collection  No.  1  of  January  15,  1913,  on  corn  meal 
agar,  some  of  the  oogonia  were  irregular  in  outline) ;  diameter  about 
40-93;x,  most  about  50-65'j.,  a  large  part  of  them  breaking  off  more  or 
less  completely  from  the  hyphae  and  from  each  other  after  the  maturity 
of  the  eggs;  walls  yellowish-brown  when  old,  smooth,  slightly  or  not 
at  all  pitted.  Eggs  1-12  in  an  oogonium,  mostly  2-6,  17.7-33.5^.  in 
diameter,  average  about  23-25^,  extremes  sometimes  occurring  in  the 
same  oogonium,  yellowish-brown,  centric,  with  two  rows  of  small  drop¬ 
lets  all  the  way  around  or  subcentric,  with  one  row  on  one  side  and  two  on 
the  other.  Gemmae  abundant  in  all  cultures,  spherical,  pear-  or  club- 
shaped,  very  often  borne  in  chains;  upon  change  of  condition  they  may 
become  sporangia,  discharging  their  spores  through  a  lateral  papilla. 
Antheridia  not  developed. 

Easily  distinguished  from  all  others  by  the  yellowish-brown 
oogonia  borne  in  chains  which  separate  wholly  or  in  part  from  each 
other  at  an  early  stage,  and  by  the  absence  of  antheridia.  DeBary ’s 
figure  does  not  show  the  structure  of  the  eggs.  The  species  has  not  been 
recognized  heretofore  in  America. 

Not  rare  in  ponds,  meadows,  and  small  streams,  such  as  pond  across 
road  in  front  of  cemetery,  branch  back  of  athletic  field,  and  Glen  Burnie 
meadow.  Collected  in  Chapel  Hill  26  times  between  February  29,  1912, 
and  December  16,  1913  (see  table,  p.  14).  Found  several  times  since. 

This  is  undoubtedly  the  true  S.  monilifera,  and  agrees  in  all  essen¬ 
tials  with  deBary’s  description.  In  one  of  our  collections  (marsh  at  foot 
of  Lone  Pine  hill,  February  17,  1921)  a  good  many  of  the  oogonia  with 
young  eggs  were  parasitized  by  the  penetration  of  a  slender,  non-septate 
fungus  which  destroyed  the  eggs  and  completely  filled  the  oogonia  with 


PLATE  24 


PLATE  24 

ISOACHLYA  ECCENTRIC  A 


Fig.  I.  Cylindrical  oogonium  with  four  eggs  inside  an  empty  sporangium.  X  447. 

Fig.  2.  An  empty  dictiosporangium.  X  167. 

Fig.  3.  Irregular  oogonia.  X  247. 

Fig.  4.  A  thread  showing  empty  sporangia,  sprouting  spores  and  one  empty  cyst  near 
top,  00  onia  on  lateral  stalks  and  intercalary  oogonia.  X  247. 

Fig.  5.  Part  of  a  thread  showing  a  single  oogonium  and  a  chain  of  three.  X  247. 

Fig.  6.  A  thread  showing  oogonia  before  and  after  eggs  are  formed  and  a  gemma  at 

the  end.  X  167. 

Fig.  7.  A  cluster  of  empty  sporangia,  X  167. 

Fig.  8.  A  compound  sporangium.  X  167. 

Fig.  9.  A  group  of  empty  sporangia.  X  167. 

Fig.  10.  A  gemma  after  emptying  as  a  sporangium.  X  247. 

Fig.  11.  Three  empty  sporangia.  X  247. 

Fig.  12.  An  empty  sporangium  proliferating  internally  by  two  threads  which  bear  young 
oogonia.  X  247. 

Fig.  13.  Two  .  mpty  sporangia  from  transformed  gemmae.  X  247. 

Fig.  14.  An  immature  oogonium  and  a  forked  gemma.  X  247. 

Fig.  15.  Two  spores  showing  cilia  in  first  swimming  stage.  X  720. 

Fig.  16.  An  oogonium  showing  one  pit  and  a  mature  eccentric  egg.  X  720. 


PLATE  24 


ISOACHLYA  ECCENTRICA. 


•V 


•: 


•  .■ 


PLATE  25 


PLATE  25 

ISOACHLYA  MONILIFERA 

Fig.  i.  Stalked  oogonia.  X  503. 

Fig.  2.  Oogonia  which  were  in  a  chain  but  have  now  fallen  apart.  X  278. 
Fig.  3.  Two  oogonia,  one  inside  an  empty  sporangium.  X  319. 

Fig.  4.  Oogonia  in  a  chain.  X  503. 

Fig.  5.  Sporangia  and  gemma.  X  278. 

Eig.  6.  Oogonia  and  gemmae.  X  278. 

Fig.  7.  Oogonia  in  a  chain.  X  278. 

Fig.  8.  Oogonium  of  odd  shape.  X  188. 

Fig.  9.  Sporangia  and  young  oogonium.  X  278. 

Fig.  10.  Sporangium  and  young  oogonium.  X  278. 

Fig.  11.  Oogonium  of  odd  shape.  X  188. 

Fig.  12.  Oogonia  and  gemmae  in  chain,  X  278. 

Fig.  13.  Oogonium  with  a  long  stalk.  X  278. 

Fig.  14.  Sporangium  and  young  oogonia.  X  278. 

Fig.  15.  A  mature  egg.  X  810. 


ISOACHLYA  MONILIFERA 


ISOACHLYA 


89 


a  compacted  complicated  growth,  making  them  appear  somewhat  like 
sporangia  with  spores.  The  parasite  recalls  a  Pythium,  but  no  repro¬ 
ductive  stages  were  seen.  In  Humphrey’s  reference  to  the  species 
(which  he  had  not  found)  he  speaks  of  the  separation  of  the  oogonia 
or  their  initials  as  if  it  always  occurred.  This  is  incorrect,  as  they  per¬ 
haps  more  often  hang  together  loosely  by  an  angle  of  the  stalk  after 
bending  partly  to  one  side.  DeBary’s  figures  (pi.  9,  fig.  6)  show  the 
oogonia  still  in  chains  though  the  eggs  are  fully  formed.  It  is  also  not 
the  case,  as  Humphrey  supposed,  that  all  the  elements  of  a  chain  of 
initials  necessarily  have  the  same  fate.  Both  oogonia  and  gemmae 
are  often  combined  in  a  chain.  The  tendency  to  constriction  is  sometimes 
shown  even  in  the  sporangia,  as  in  pi.  50,  fig.  10.  For  other  illustration 
see  Minden  (’12),  fig.ig  on  p.  520.  As  in  I.  unisporci  the  spores  emerge 
slowly  from  the  sporangium  with  the  cilia  end  directed  backward. 
After  emergence  most  of  the  spores  show  a  very  sluggish  movement 
close  to  the  tip  for  a  minute  or  so  and  then  swim  more  actively  away. 
Not  rarely  a  few  encyst  without  active  swimming. 

Isoachlya  toruloides  easily  differs  in  the  presence  of  antheridia  (though 
often  in  small  numbers),  in  the  much  less  frequent  occurrence  of  chained 
oogonia  and  in  the  paler  walls  of  the  oogonia.  See  remarks  under  that 
species. 

As  in  S.  asterophora  and  A  planes  Treleaseanus  the  sporangia  are  as 
a  rule  exceedingly  scarce  or  absent.  In  one  of  our  collections  made  in 
1921  the  numerous  cultures,  continued  for  months  on  various  media, 
failed  to  produce  a  single  sporangium. 

The  following  four  cultures  were  made  from  No.  1  of  January  15, 
1913: 

On  corn  meal  agar.  Good  growth  and  many  fine  gemmae.  No  oogonia.  (No.  2  of 
February  17,  1921,  produced  many  oogonia  with  good  eggs,  also  gemmae). 

In  equal  parts  maltose  5%  and  peptone  .01%.  Good  growth  about  one  inchin  diameter. 
The  only  reproduction  was  a  very  abnormal  attempt  to  form  gemmae  or  eggs.  The  tips 
swelled  and  only  the  apical  half  of  the  swelling  was  cut  off.  These  tip  cells  generally 
remained  filled  with  moderately  dense  protoplasm,  but  in  a  few  cases  eggs  were  formed 
in  them. 

In  egg  yolk  broth.  Good  dense  growth.  Many  inflated  oogonia,  about  >2  with  good  eggs, 
a  good  many  enlargements  as  in  above  experiment,  with  cross  wall  in  middle  or  nearer 
tip  of  base.  Some  of  these  had  eggs  in  tip  cell.  No  other  reproduction. 

On  corn  meal  egg  yolk  agar.  Growth  strong,  covering  the  agar,  many  oogonia,  nearly  all 
with  good  eggs.  Many  gemmae.  Oogonia  almost  always  single  and  terminal.  When 
chains  were  formed  all  except  the  tip  one  remained  as  gemmae.  A  good  many  oogonia 
were  irregular  in  shape  and  so  far  this  is  the  only  medium  in  which  this  was  the  case. 
See  figs.  8  and  11. 

The  next  two  cultures  were  made  from  No.  6  of  March  27,  1914: 


90 


THE  SAPROLEGNIACEAE 


On  an  ant  in  distilled  water.  Good,  but  rather  small  growth,  many  sporangia,  no  eggs  and 
few  gemmae. 

On  corn  meal  agar.  Good  growth  and  many  fine  gemmae,  three  or  four  oogonia  were  found, 
the  eggs  not  very  normal  looking  and  some  going  to  pieces. 

The  following  experiments  were  made  to  determine  the  best  method 
of  preserving  live  cultures: 

Culture  (No  i  of  January  15,  1913)  put  in  vial  on  corn  meal  agar  on  March  18,  1913.  and 
was  found  to  be  dead  December  1,  1913. 

Culture  (No.  I  of  January  15,  1913)  was  put  in  jar  on  March  3,  1913.  Test  for  life  was 
made  September  18,  1917,  by  dropping  in  mushroom  grub,  but  no  growth  appeared. 


PROTOACHLYA  n.  genus 

This  genus  is  established  on  a  species  collected  at  Chapel  Hill  and 
previously  described  as  Adilya.  It  may  be  defined  as  follows: 

Hyphae  more  delicate  than  in  Adilya;  sporangia  subcylindrical  to 
clavate  or  flask-shaped,  blunt  and  usually  thickest  beyond  the  middle, 
proliferating  like  a  cyme,  as  in  Adilya ,  and  also  less  frequently  by  growth 
through  the  empty  sporangia,  as  in  Saprolegnia.  Spores  diplanetic,  on 
emerging  ciliated  and  all  or  some  showing  sluggish  or  less  often  active 
motion,  some  remaining  attached  in  an  irregular  clump  to  the  tip  of  the 
sporangium.  Oogonia  borne  singly,  the  great  majority  on  short  lateral 
stalks  from  the  main  hyphae  and  with  or  without  a  few  pits;  eggs  usually 
few,  centric.  Antheridia  androgynous  or  diclinous,  typically  pyriform 
with  their  tips  applied  to  the  oogonia.  Gemmae  spherical  to  pyriform  or 
elongated.  Vegetative  behavior  not  not’ceably  different  from  other  gen¬ 
era. 

The  genus  is  of  great  interest  as  indicating  a  possible  common  an¬ 
cestor  of  several  existing  groups.  It  seems  almost  exactly  intermediate 
between  Saprolegnia  and  Adilya.  The  genus  normally  exhibits  not  only 
characters  of  several  genera,  but  combines  what  have  been  considered 
antithetic  characters,  as  both  cymose  and  inter-sporangial  proliferation 
of  sporangia  and  motile  and  motionless  spores  on  emerging.  When  Adilya 
paradoxa  was  first  described  (Mycologia  6:  285.  1914)  we  were  reluctant 

to  introduce  a  new  genus  based  on  one  species,  and  so  retained  it  in  Adilya, 
with  considerable  violence  to  the  elasticity  of  that  genus.  Further  study 
of  the  species  has  convinced  us  that  it  should  be  separated  from  Adilya. 
Kauffman  (’21,  p.  231)  transfers  it  to  Isoachlya ,  but  this  we  feel  sure  is  a 
mistake. 

Protoadilya  differs  from  Adilya  in  the  motility  of  some  or  all  of  the 
spores  on  emerging,  the  not  infrequent  internal  proliferation  of  the 
sporangia  and  their  thick  rounded  tips,  the  presence  of  spherical  or  pyriform 


PROTOACHLYA 


91 


gemmae,  and,  from  all  except  the  Racemosa  group,  in  the  egg  structure. 
It  differs  from  Saprolegnia  in  the  non-motility  of  some  of  the  spores  on 
emerging,  in  the  predominant  sympodial  proliferation  of  the  sporangia, 
and  in  the  frequent  occurrence  of  dictiosporangia.  From  Isoachlya  it  dif¬ 
fers  in  the  non-motility  of  some  of  the  spores  on  emerging,  in  the  frequent 
occurrence  of  dictiosporangia,  in  the  absence  of  chained  oogonia  and  in  the 
presence  of  antheridia  on  all  oogonia  (normally).  The  relationships  of  the 
genus  are  not  obvious.  Either  Dictyuchus  or  the  Racemosa  group  of 
Achlya  seems  nearest. 

1.  Protoachlya  paradoxa  n.  comb.* 

Achlya  paradoxa  Coker.  Mycologia  6:  285,  pi.  146.  1914. 

Isoachlya  paradoxa  (Coker)  Kauff.  Amer.Journ.  Bot.  8:  231.  1921. 

Plates  26,  27  and  28 

Plant  delicate;  hyphae  straight,  slender,  and  little  branched,  the 
larger  threads  having  a  diameter  of  about  37[i  below  on  a  mushroom 
grub;  many  much  smaller,  the  average  being  about  1  o—  1 5 ;  sporangia 
plentiful  at  all  stages,  narrowly  club-shaped  and  largest  at  the  distal 
end,  which  is  about  20-30^  in  diameter,  rounded  at  the  tip,  and  fur¬ 
nished  with  a  distinct  but  short  papilla;  secondary  sporangia  formed 
usually  by  cymose  branching  beneath  the  old  ones,  but  occasionally 
also  by  proliferation  through  the  empty  ones,  exactly  as  in  Saprolegnia , 
except  that  the  new  sporangia  are  formed  entirely  outside  the  old  ones; 
dictiosporangia  not  rare.  Spores  diplanetic,  formed  in  several  rows  as 
in  Saprolegnia  and  Achlya,  on  emerging  all  ciliated,  but  varying  greatly 
in  behavior — some  swimming  away  as  a  rule,  the  others  remaining  attached 
in  an  irregular  group  to  the  tip  of  the  sporangium.  Oogonia  produced 
on  the  tips  of  short  lateral  branches,  usually  near  the  base  of  the  main 
hyphae,  sometimes  intercalary;  spherical,  the  diameter  32-80:1  (one  seen 
I00[o.  thick),  sometimes  elongated  or  flask-shaped  especially  when  inter¬ 
calary;  their  walls  smooth  and  usually  with  a  few  pits  (two  or  three  often 
visible  in  addition  to  the  thin  places  where  the  antheridia  are  attached);! 
eggs  centric,  usually  two  or  four,  often  six,  and  rarely  one  or  eight  or  ten 
(twelve  seen  once) ;  their  diameter  from  22-37:1,  averaging  about  30^;  an¬ 
theridia  always  present,  generally  several  and  sometimes  so  numerous  as 

*  Most  of  the  data  given  herewith  for  this  species  is  taken  from  the  original  publication, 
as  is  also  plate  24  in  part. 

fin  the  original  description  the  walls  were  erroneously  said  to  be  without  pits.  This 
is  true  only  for  many  of  the  smaller  ones. 


92 


THE  SAPROLEGNIACEAE 


completely  to  cover  the  oogonia,  short,  club-shaped,  or  often  tuberous  and 
branched,  terminating  slender  branches  of  diclinous  or  rarely  androg¬ 
ynous  origin  which  at  times  show  a  tendency  to  twine  about  the  oogonial 
branches;  antheridial  tubes  enter  the  oogonia,  run  among  the  eggs,  and 
probably  fertilize  them. 

Found  35  times  in  branches,  marsh  borders,  etc.,  often  with  algae, 
such  as  Vaucheria,  as  in  brook  near  east  gate  of  the  University  campus, 
Arboretum  branch,  etc. 

In  fig.  I  the  sporangia  are  shown  in  a  group,  after  the  manner  of 
AcJilya.  The  bending  of  the  sporangia  that  is  quite  noticeable  in  this 
figure  is  characteristic,  though  not  always  so  pronounced. 

In  figs.  2  and  3  are  shown  the  proliferation  of  sporangia  by  both 
the  Achlya  and  Saprolegnia  methods  on  the  same  thread.  The  latter 
method  is  rare.* 

The  behavior  of  the  spores  on  emerging  is  remarkable  and  very 
variable.  The  usual  behavior  is  for  some  of  the  spores,  perhaps  a  half 
or  a  third,  to  swim  slowly  away  on  emerging,  the  others  remaining  attached 
to  the  sporangium  mouth  and  encysting  there.  In  regard  to  their  action 
we  give  the  following  quotation  somewhat  modified  from  notes  in  Mycologia 
(1.  c.,  p.  286)  made  at  the  moment  of  observation: 

The  spores  emerge  somewhat  elongated  and  may  be  seen  to  bend  backward  at  the 
ends  and  fuse  into  a  pear-shaped  spore,  as  is  the  case  in  Leptolegnia.  The  spores  as  a  rule 
move  sluggishly  and  most  of  them  soon  settle  to  the  bottom  near  the  sporangium  mouth  and 
encyst,  also  a  lot  of  inactive  ones  are  often  left  in  a  group  that  sticks  to  the  sporangium 
mouth,  giving  the  effect  of  Achlya. 

We  find  cases  where  all,  or  nearly  all,  of  the  spores  group  themselves  at  the  mouth 
exactly  as  is  typical  of  Achlya.  When  conditions  are  unfavorable  the  spores  sometimes 
do  not  emerge  at  all  and  in  such  cases  they  sprout  in  position. 

Noticed  two  sporangia  empty  near  together.  In  one  the  spores  grouped  themselves 
at  the  mouth  of  the  sporangium  just  as  in  Achlya ,  except  that  a  few  of  the  outermost  gently 
rocked  themselves  away  a  little  distance  from  the  main  mass  and  then  settled  down.  The 
spores  that  remained  in  a  mass  at  the  tip  of  the  sporangium  also  showed  a  very  slight  rock¬ 
ing  movement,  thus  proving  the  presence  of  cilia,  but  in  a  couple  of  minutes  they  became 
quite  still.  In  the  other  sporangium  the  spores  charged  out  with  great  rapidity  and  every 
one  dashed  rapidly  away. 

A  sporangium  emptied  and  all  the  spores  sank  slowly  to  the  bottom  of  the 
dish,  separating  themselves  considerably  by  a  gentle  rocking  motion.  After  settling 
individuals  would  move  spasmodically  at  intervals,  turning  and  jerking,  but  none  swam 
actively  or  any  distance.  This  interrupted  movement  continued  for  at  least  a  half  hour 
after  emergence. 

A  sporangium  emptied  (temperature  89°  F.)  and  all  the  spores  were  expelled  to  some 
distance  from  the  opening,  all  remaining  in  a  group  as  if  held  lightly  together,  and  all 

*Weknowofno  reference  in  the  literature  to  internal  proliferation  of  any  kind  in  Achlya , 
except  by  Petersen  (Ann.  Mycologici  8:  520.  1910),  who  says:  “Thus  I  have  seen  zoospor¬ 
angia  which  had  proliferated  in  undoubted  species  of  Achlya We  have  found  such  prolif¬ 
eration  twice  in  A.  imperfecta. 


PLATE  26 


PLATE  26 

(All  figs,  except  4  and  7  are  Irom  Mycologia  6:  PI.  146.  19141. 

Protoachlya  paradoxa 

Fig.  I.  A  group  of  sporangia  showing  both  lateral  and  internal  proliferation.  X  335. 
Fig.  2.  Another  example  of  the  above.  X  335. 

Fig.  3.  A  sporangium  with  spores  killed  during  their  exit,  showing  cilia.  X  335. 

Fig.  4.  A  group  of  sporangia,  produced  as  in  Achlya.  X  162. 

Fig.  5.  A  group  of  empty  sporangia  of  normal  appearance.  X  335. 

Fig.  6.  Gemmae.  X  335- 

Fig.  7.  Sporangial  formation  peculiar  to  this  species.  X  370. 

Fig.  8.  An  oogonium  with  base  intercalated  in  a  hypha.  The  projection  below  is  not 
usual;  an  antheridium  was  present,  but  it  is  not  shown.  X  335. 

Figs.  9,  10  and  11.  Typical  oogonia  with  antheridia  and  fertilization  tubes.  X  335. 


PLATE  2G 


PROTOACHLYA  PARADOXA. 


I 


•• 


PLATE  27 


PLATE  27 

Protoachlya  paradoxa 

Fig.  I.  Subspherical  oogonium  with  typical  antheridia.  X  281. 

Fig.  2.  Oogonia  with  androgynous  and  diclinous  antheridia,  and  gemmae.  X  188. 
Fig.  3.  Sporangia  with  spores  sprouting  in  position.  X  281. 

Fig.  4.  A  dictiosporangium.  X  503. 

Fig.  5.  Oogonia  with  diclinous  antheridia.  X  188. 

Fig.  6.  An  oogonium  with  an  androgynous  antheridium.  X  281. 

Fig.  7.  Oogonia  with  androgynous  and  diclinous  antheridia.  X  188. 

Fig.  8.  An  oogonium  with  antheridia  arising  from  three  different  hyphae.  X  278. 
Fig.  9.  An  oogonium  showing  antheridial  tube  clearly,  and  two  ripe  eggs.  X  503. 
Fig.  10.  An  unusual  shape  of  oogonium.  X  281. 


PLATE  27 


PROTOACHLYA  PARADOXA 


PLATE  2S 


PROTOACHLYA  PARADOXA.  x  6 


PROTOACHLYA 


93 

coming  to  rest  at  once  in  a  group.  This  behavior  is  only  another  proof  of  the  fact  that 
spores  are  expelled  by  sporangial  turgor  in  this  family  and  not  by  their  own  power. 

The  existence  of  cilia  thus  indicated  by  the  behavior  of  the  spores 
was  demonstrated  by  treatment  with  potassium  iodide  solution  at  the 
moment  of  emergence.  A  sporangium  so  treated  is  shown  in  plate  26, 
fig.  3.  All  the  spores  can  be  distinctly  seen  to  have  cilia.  From  these 
observations  it  will  be  seen  that  the  behavior  of  the  spores  has  no  normal 
parallel  in  the  genus  Achlya. 

Oogonia  without  stalks  and  with  their  bases  formed  from  a  section  of 
a  hypha  are  not  at  all  rare.  Slender  upgrowths  into  the  oogonium 
from  the  partition  below  are  occasionally  seen.  Such  growths  often 
appear  in  other  species  of  Saprolegnia  and  Adilya ,  but,  while  they  give 
the  effect  of  antheridial  tubes,  they  are  apparently  quite  functionless 
except  perhaps  in  the  cases  where  a  hypogynous  antheridium  is  cut  off  (A . 
hypogyna  and  S.  hypogyna ).  The  antheridia  themselves  are  peculiar.  They 
are  sudden  enlargements  of  the  tips  of  the  antheridial  branches  and 
are  short,  thick  and  tuber-like.  They  often  proliferate,  and  usually 
by  growth  from  near  the  base  of  the  antheridial  cells  themselves.  These 
outgrowths  are  then  cut  off  as  separate  antheridia.  When  first  formed 
the  antheridia  are  well  filled  with  protoplasm  and  contrast  strongly 
with  the  almost  colorless  branches  that  bear  them.  Later  the  antheridia 
appear  almost  empty  as  if  they  had  discharged  their  contents  into  the 
eggs.  This,  however,  was  not  actually  observed.  Gemmae,  unlike  the 
oogonia,  are  not  rare,  but  appear  plentifully,  though  not  densely,  in  al¬ 
most  all  cultures.  The  majority  terminate  short  branches  and  approxi¬ 
mate  the  oogonia  in  size,  shape  and  position  (plate  26,  fig.  6) ;  others  are 
arranged  in  chains  (fig.  6)  which  are  usually  curved  or  contorted.  Elon¬ 
gated  and  irregular  forms  are  also  produced  from  somewhat  swollen  and 
knotted  segments  of  the  hyphae.  Under  ordinary  cultural  conditions, 
such  as  on  flies,  termite  ants,  gnats,  mushroom  grubs,  etc.,  in  water,  there 
is  usually  no  sexual  reproduction.  Out  of  a  hundred  cultures  perhaps 
one  would  show  a  few  oogonia,  and  their  appearance  seems  to  be  entirely 
whimsical  at  times.  For  example,  in  a  series  of  cultures  made  from 
the  same  original,  one  of  the  cultures  on  a  mushroom  grub  produced  a 
large  number  of  oogonia,  while  others  on  the  same  as  well  as  other  media 
produced  none.  On  the  other  hand,  the  oogonia  appear  rather  fre¬ 
quently  in  cultures  first  appearing  in  the  water  brought  in  with  the  collection. 
This  fact  is  illustrated  in  the  following  note  by  Mr.  J.  N.  Couch. 

“On  July  25,  1918,  I  brought  in  ten  glasses  of  water  containing  trash,  leaves,  sticks, 
etc.  The  material  was  put  into  crystallizing  dishes  and  in  order  to  cover  the  bottom  well 
more  water  was  added  from  the  spigot,  and  four  or  five  grubs  were  dropped  into  each  dish. 
A  few  days  later  it  was  found  that  7  out  of  the  10  collections  had  a  fine  growth  of  A.  para- 
doxa  with  abundant  oogonia  and  a  fine  lot  of  typical  sporangia.  As  a  rule  A.  paradoxa 


94 


THE  SAPROLEGNIACEAE 


resists  quite  stubbornly  all  efforts  to  produce  oogonia  by  artificial  methods.  Sub-cultures 
from  the  above  have  been  made  on  grubs  in  pure  water  and  few  cultures  produced  any 
oogonia  at  all.” 

A  number  of  experiments  have  been  made  to  induce  the  formation 
of  oogonia.  The  results  of  some  of  these  are  as  follows: 

On  a  bit  of  whole  egg  agar  in  distilled  water.  Growth  vigorous  and  healthy.  Sporangia  abun¬ 
dant,  emptying  normally  and  proliferating  laterally  from  below.  No  oogonia  or  gemmae. 
On  a  bit  of  whole  egg  agar  in  distilled  water.  Growth  vigorous,  reaching  a  diameter  of  4 
cm.  Sporangia  slow  to  form,  but  after  full  growth  appearing  rather  plentifully.  Gem¬ 
mae  of  usual  shape  present,  but  not  plentiful.  No  oogonia. 

On  a  bit  of  hard  boiled  egg  yolk  in  distilled  water.  Growth  vigorous,  reaching  a  diameter  of 
4  cm.  Sporangia  abundant  and  formed  earlier  than  in  culture  above.  Gemmae 
plentiful.  Oogonia  present,  but  scarce.  Antheridia  of  diclinous  origin.  As  this  was 
a  culture  from  a  single  spore,  the  presence  of  antheridia  proves  that  the  plant  is  not 
dioecious. 

On  a  bit  of  whole  egg  agar  in  spring  water.  Growth  vigorous  and  strong.  Many  gemmae. 
No  sexual  reproduction. 

On  fly  in  spring  water.  Growth  vigorous.  Many  sporangia,  all  proliferating  from  side 
below  as  in  Achlya.  No  gemmae. 

On  corn  meal  agar.  Growth  extensive,  filling  dish.  Aerial  branches  nearly  reaching  cover, 
but  not  dense.  Only  gemmae  present. 

In  5  per  cent  maltose  +  0.1  per  cent  peptone  solutions  mixed  half  and  half.  Growth 
vigorous  and  healthy.  A  few  small  sporangia  were  formed,  but  the  spores  were  only 
imperfectly  discharged.  Also  a  few  of  the  characteristic  knob-like  gemmae. 

On  corn  meal  agar  in  tightly  stopped  sterile  bottle.  Growth  vigorous,  extending  across 
bottle  and  making  a  mold-like  aerial  growth  an  inch  high.  On  examination  there 
were  found  only  single  gemmae,  most  of  which  were  quite  empty,  they  having  sprouted 
by  a  slender  thread  about  3[x  in  diameter.  In  fact  all  the  growth  was  remarkably 
slender  (3[j.  in  diameter),  enlarging  to  normal  size  only  just  below  the  gemmae. 

On  corn  meal  and  egg  yolk  agar.  Growth  very  strong,  covering  dish  and  developing  abun¬ 
dant  aerial  hyphae  that  reached  the  cover.  No  reproduction  of  any  kind. 

The  following  six  cultures  were  all  made  on  termites  in  distilled 
water  with  the  salt  added  as  indicated : 

In  0.1  per  cent  KN03.  Growth  good.  Normal  sporangia,  discharging  and  spores  taking 
second  swim,  as  was  the  case  in  all  except  the  last  of  these  six  cultures.  Many  good 
gemmae  of  usual  shape,  the  larger  ones  having  a  tendency  to  form  the  cross  wall  some 
way  up  from  the  base.  No  sexual  reproduction. 

In  0.1  per  cent  KH2PO4.  Growth  good.  Many  gemmae.  No  sexual  reproduction. 

In  0.1  per  cent  NajHPCfi.  Growth  good.  A  good  many  gemmae,  but  not  so  numerous  as 
in  the  preceding  cultures.  No  sexual  reproduction. 

In  0.1  per  cent  Ca3(P04)2.  Growth  good.  Many  gemmae  of  usual  shape.  No  sexual  re¬ 
production. 

In  0.1  per  cent  Ca(N03)2.  Growth  good.  Many  gemmae.  No  sexual  reproduction. 

In  0.1  per  cent  K2SO4.  Growth  slight.  Culture  infested  with  fungus.  Sporangia  formed 
but  not  discharging.  A  few  gemmae.  No  sexual  reproduction. 


ACHLYA 


95 

The  following  seven  cultures  were  all  made  on  hard  boiled  egg  yolk 
in  distilled  water  with  the  chemical  added  as  indicated: 

In  o.l  per  cent  KN03.  Strong  growth.  No  sporangia.  A  few  good  gemmae.  No  sexual 
reproduction. 

In  o.l  per  cent  KH2P04.  Growth  good.  A  very  few  sporangia  with  normal  discharge. 
No  gemmae  or  sexual  reproduction. 

In  o.l  per  cent  Na2HP04.  Strong  growth.  Abundant  sporangia  proliferating  repeatedly 
and  discharging  normally.  A  very  few  gemmae.  No  sexual  reproduction. 

In  o.l  per  cent  K2S04.  Strong  growth.  Sporangia  plentiful.  Gemmae  abundant.  No 
sexual  reproduction.  One  sporangia  was  seen  discharging.  The  emergence  was 
rather  slow,  and  the  last  few  spores  were  very  slow  and  showed  obvious  swimming 
movements  in  the  sporangium  on  escaping.  About  a  dozen  clung  to  the  tip  of  the 
sporangium.  The  others  spread  in  a  1  ose  flock,  showing  slow  movements,  and  every 
now  and  then  one  would  swim  briskly  away. 

In  o.l  per  cent  Ca3(P04)2.  Strong  growth.  Many  sporangia,  quite  norma1.  A  very  few 
gemmae.  No  sexual  reproduction.  Several  sporangia  seen  to  dis  harge.  In  two 
cases  six  spores  detached  themselves  and  moved  away,  in  another  case  four. 


ACHLYA  Nees  v.  Esenbeck,  1823,  p.  514. 

Resembling  Saprolegnia  essentially  in  size,  growth  and  appearance 
of  vegetative  parts  and  as  now  constituted  approaching  that  genus  closely 
in  some  species.  Sporangia  typically  (except  in  the  Racemosa  group) 
broadest  in  the  middle  or  towards  the  base,  gradually  pointed,  not  in¬ 
creased  from  within  others  but  by  lateral  branching  from  below  the  older 
ones,  at  times  in  close  clusters,  again  in  more  interrupted  sympodial 
arrangement.  Spores  on  leaving  the  sporangium  coming  to  rest  at 
once,  or  after  a  short  period  of  slow  rocking,  in  a  hollow  sphere  or  irregu¬ 
lar  cluster  (in  several  species  at  least  furnished  with  cilia  during  emer¬ 
gence),  encysting  there  and  after  a  few  hours  swimming  again  as  in 
Saprolegnia.  Oogonia  borne  variously  as  in  Saprolegnia,  with  or  with¬ 
out  pits  or  papillae.  Eggs  formed  of  all  the  contents  of  the  oogonia 
and  not  completely  filling  them,  one  to  many;  varying  in  structure  with 
the  different  groups.  Antheridia  of  near  or  distant  origin,  androgynous 
or  diclinous,  in  a  few  species  absent;  fertilizing  tubes  usually  present. 
Fertilization  has  been  demonstrated  in  A.  americana  var.  cambrica  and  A. 
polyandra  Hildb.  by  Trow,  and  in  A.  deBaryana  by  Trow  and  by  Miicke 
(see  these  species  for  details).  We  have  observed  the  passage  of  living 
material  from  the  antheridium  into  the  egg  of  A.  Orion,  and  it  is  very 
probable  that  fertilization  occurs  in  a  number  of  other  species. 

The  species  of  Achlya  can  be  divided  very  naturally  into  several 
distinct  groups  or  sub-genera  which  are  separated  by  the  internal  struc- 


96 


THE  SAPROLEGNIACEAE 


ture  of  the  eggs  and  the  form  of  the  antheridial  branches  and  antheridia. 
One  of  the  species  heretofore  included  we  have  removed  to  our  new 
genus  Protoachlya.  As  it  remains  after  this  removal,  the  genus  Achlya 
contains  four  primary  groups  that  we  are  considering  as  sub-genera, 
under  the  more  typical  of  which  one  may  recognize  two  well-defined 
assemblies.  One  of  the  sub-genera  (Centro achlya)  is  so  sharply  delimited 
as  easily  to  qualify  for  a  new  genus  were  one  inclined  to  make  it. 
As  small  and  numerous  genera  are  a  nuisance  to  everyone  except  the 
most  extreme  specialist  (and  a  nuisance  to  him  except  in  his  own  field) 
we  gladly  refrain  from  increasing  the  number  any  further  than  seems  to 
us  necessary  in  order  to  retain  a  clear  conception  and  definition  of  the 
old  genus  Achlya.  Achlya  paradoxa,  which  we  are  removing  to  Pro¬ 
toachlya,  is  not  a  good  Achlya,  as  a  part  of  its  spores  swim  away  on 
emerging. 

As  to  the  correct  position  of  A.  glomerata  there  is  some  doubt.  Its 
odd  little  oogonia,  single  egg,  and  antheridia  as  in  the  Racemosa  group 
seem  to  set  it  off  distinctly.  It  may  be  a  lead  toward  Aphanomyces. 

As  the  words  centric  and  eccentric  have  both  been  used  to  cover 
quite  different  organizations  of  the  eggs,  one  must  await  more  careful 
study  to  be  sure  of  the  position  of  certain  European  species  in  which  the 
eggs  are  described  as  centric  or  weakly  eccentric. 

In  attempting  to  put  into  order  the  members  of  the  Prolifera-deBary- 
ana  group  we  meet  with  some  of  the  most  perplexing  problems  in  the 
entire  family.  Either  deBary  was  entirely  too  rigid  in  his  descriptions 
of  A.  prolifera,  and  A.  deBaryana  (his  A.  polyandra )  and  failed  to  allow 
for  a  certain  amount  of  normal  variation,  or  there  are  more  than  five 
times  as  many  species  or  sub-species  (or  what  not)  in  the  close  group 
represented  by  these  two  species  than  he  described,  a  fact  not  sur¬ 
prising  in  itself  if  it  were  not  for  certain  strange  inconsistencies  in  their 
distribution. 

With  the  great  majority  of  the  good  species  of  the  older  European 
botanists  already  known  to  occur  in  America  with  little  or  no  discrep¬ 
ancies,  it  is  odd  indeed  that  A.  prolifera  and  A.  deBaryana,  the  two  most 
common  European  Achlyas  (according  to  deBary,  Fischer,  Minden  and 
others),  should  so  far  not  have  been  recognized  in  America.  Instead 
we  have  several  species  (or  forms)  very  close  to  them,  indeed,  but  failing 
to  agree  with  them  in  one  or  more  characters  most  emphasized  in  their 
descriptions.  Achlya  proliferoides  is  just  like  A.  prolifera  except  that 
the  antheridial  branches  are  not  always  diclinous  and  do  not  wrap  them¬ 
selves  so  extensively  about  the  oogonia,  and  the  number  of  eggs  in  an 
oogonium  is  small,  nearly  always  two  to  six.  On  the  other  hand,  among 
their  many  striking  resemblances  they  are  the  only  two  species  we  have 


ACHLYA 


97 

seen  that  show  the  conspicuous  winding  of  the  antheridial  branches 
about  the  hyphae.*  Achlya  imperfecta  is  just  like  A.  proliferoides  ex¬ 
cept  that  it  has  as  many  androgynous  as  diclinous  antheridia  and  that 
the  antheridial  branches  do  not  wind  about  the  hyphae.  These  two 
also  show  the  odd  peculiarity  (shared  to  a  less  extent  by  A.  flagellata ) 
of  failing  to  develop  the  great  majority  of  their  eggs  to  maturity.  It 
would  seem  that  such  a  character  could  not  fail  to  attract  remark  if 
observed  in  related  European  plants, f  but  of  this  we  cannot  be  sure. 
This  peculiarity  and  the  great  variability  of  this  group  suggest  the  possi¬ 
bility  of  a  hybrid  origin.  See  Science,  April  4,  1914,  The  Mutation  Myth. 

The  main  difficulty  that  led  Humphrey  to  set  up  his  A.  americana 
was  the  supposed  absence  of  pits  in  the  European  plant,  as  stated  by 
all  authors  until  recently.  In  1910  Petersen  (’10,  p.  524)  reported  a  plant 
from  Denmark  like  A.  polyandra  deBary  except  that  the  oogonium  wall 
was  pitted,  and  lists  it  as  A.  polyandra  forma  Americana ,  supposing  it  to 
be  Humphrey’s  plant  and  reducing  it  to  a  variety  (egg  measurements 
not  given).  He  did  not  find  a  similar  plant  without  pits.  As  the  pits  are 
very  inconspicuous  and  are  absent  on  many  of  the  oogonia  it  is  easy  to  see 
how  deBary  might  have  overlooked  the  pits  if  they  were  absent  on  cer¬ 
tain  oogonia  especially  examined  for  this  point.  The  pits  are  as  whim¬ 
sical  as  in  A.  flagellata  and  are  sometimes  absent  over  a  large  part  of  a 
culture  and  present  in  another  part.  Most  authors  since  deBary,  in 
following  his  authority,  might  easily  have  been  misled.  The  pits  are 
as  a  rule  practically  invisible  under  low  power  and  are  not  so  obvious 
under  any  power  as  in  many  Saprolegnias.  Horn  found  (’04,  p.  227) 
that  while  his  plant  was  without  pits  in  normal  media,  obvious  pits 
appeared  when  cultivated  in  peptone  and  in  grape  or  cane  sugar.  In 
such  cases  pitted  and  unpitted  oogonia  appeared  on  the  same  hyphae, 
as  is  normally  the  case  in  our  A.  imperfecta,  A.  flagellata,  and  A.  con- 
spicna. 

The  following  brief  diagnosis  of  known  forms  of  the  Prolifera  group 
showing  the  principal  differences  may  be  of  interest: 

Achlya  americana :  Wall  pitted ;  antheridial  branches  practically  all  androgynous,  branched, 
but  short;  eggs  small,  of  moderate  number. 

Achlya  americana  var.  cambrica :  Wall  conspicuously  pitted;  antheridial  branches  all  (.J) 
androgynous,  on  all  oogonia,  short  and  rather  simple ;  eggs  of  medium  size  (23-26/9 
and  moderate  number  (usually  3-8). 


*  Coiling  may  occur  to  a  slight  extent  in  almost  any  species,  as  in  P.  paradoxa  (pi.  26, 
fig-  n)-  See  also  similar  coiling  in  A.  polyandra  as  shown  by  Cornu  (’72,  pi.  1). 

■[Horn  shows  proliferating  oogonia  and  abnormal  empty  ones  in  a  plant  he  took  to  be 
a  form  of  A.  deBary  ana  (’04,  fig.  19). 


98  THE  SAPROLEGNIACEAE 

Achlya  dcBaryana  (A.  polyandra  deB.),  typical  form:  Wall  not  pitted:  antheridial  branches 
almost  always  androgynous,  but  never  arising  from  oogonial  stalks,  much  branched, 
not  winding  about  the  hvphae;  eggs  small  (18-26^)  and  numerous. 

Achlya  dcBaryana ,  Horn’s  form:  Wall  not  pitted  (except  in  certain  chemicals);  antheridial 
branches  mostly  diclinous,  but  also  androgynous,  long  and  branched;  eggs  small,  few 
(1-5,  usually  2  or  3  normally:  in  peptone  up  to  20).  This  is  nearest  A.  imperfecta 
and  is  probably  the  same. 

Achlya  Orion:  Antheridia  practically  all  androgynous,  present  on  about  75%  of  the  oogonia; 
eggs  usually  1  or  2,  most  about  33-36/x  thick. 

Achlya  prolifera:  Wall  pitted;  antheridial  branches  all  diclinous,  much  branched,  winding 
about  hyphae;  eggs  small,  rather  numerous. 

Achlya  a  planes :  Wall  with  or  without  pits ;  antheridial  branches  long  and  branched,  all 
diclinous;  eggs  rather  few,  large  (24-31. 5/*);  spores  emerging  as  usual  or  remaining 
in  the  sporangium,  in  either  case  without  a  swimming  stage. 

Achlya  proliferoides:  Wall  pitted;  antheridial  branches  mostly  diclinous,  long  and  much 
branched,  winding  about  hyphae;  eggs  small,  few,  mostly  failing  to  mature. 

Achlya  flagellata:  Wall  pitted;  antheridial  branches  more  often  diclinous  than  androgynous, 
perhaps  about  three  times  as  often  but  varying  in  this  respect,  long  and  much  branched; 
eggs  large,  of  moderate  number. 

Achlya  imperfecta:  Wall  pitted;  antheridial  branches  as  often  androgynous  as  diclinous, 
frequently  long  and  much  branched,  not  winding  about  the  hyphae,  often  arising  from 
the  oogonial  stalks;  eggs  few,  small,  mostly  failing  to  mature  in  our  form  (this  point 
not  mentioned  by  Minden). 

Achlya  Klebsiana:  Wall  not  pitted;  antheridial  branches  all  diclinous,  long  and  much 
branched  (apparently),  not  wrapped  about  the  hyphae;  eggs  of  moderate  size  and 
number. 

Achlya  caroliniana:  Wall  not  pitted;  antheridial  branches  absent;  eggs  few,  small. 

Natural  key  to  the  Species  of  Achlya* 

Sub-genus  Centroachlya:  Eggs  truly  centric  with  a  complete  circle  of  small  droplets  sur¬ 
rounding  the  protoplasm  in  A.  racemosa,  A.  colorata,  and  A.  hypogyna,  subcentric 
in  A.  radio sa.  f  Antheridia  present  in  all  but  one  species,  androgynous,  borne  on 
short  and  usually  simple  or  little  branched  threads  which  arise  in  great  part  from 
the  oogonial  stalks  (except  in  one  species).  Oogonial  walls  yellow.  Sporangia 
typically  cylindrical  or  slightly  thicker  near  the  tip;  spores  not  forming  a  hollow 
sphere  on  emerging  (in  Chapel  Hill  species). 

Racemosa  Group:  The  only  group  of  the  sub-genus  and  similarly  defined 

Oogonia  smooth;  eggs  commonly  about  22^  thick . A.  racemosa  (2) 

Oogonia  more  or  less  thickly  set  with  blunt  or  short  papillae  or  spines  (a  part 
of  the  oogonia  sometimes  smooth) 

Hypogynal  cell  often  present . A.  hypogyna  (1) 

Hypogynal  cell  absent 

Antheridia  on  all  the  oogonia,  and  nearly  always  arising  from  the  stalk, 

eggs  usually  1-4,  their  diameter  as  a  rule  30-37^ . A.  colorata  (3) 

Antheridia  on  all  the  oogonia,  arising  from  their  stalks  or  from  the  main 
threads;  eggs  1  (rarely  2  or  3),  their  diameter  usually  34-37^ 

A.  radiosa  (p.  139) 

*The  position  of  A.  Iloferi  is  entirely  conjectural  until  the  structure  of  the  eggs  is 

known.  It  is  therefore  omitted  from  the  following  scheme.  For  artificial  key  see  p.104. 

American  species  are  followed  by  a  number,  European  by  a  page  reference, 
j  1  he  structure  is  not  accurately  known  in  the  other  species. 


ACHLYA 


99 


Antheridia  usually  on  all  oogonia,  and  arising  as  a  rule  from  the  main 

threads;  eggs  4-6,  their  diameter  about  25/j . A.  papillosa  (4) 

Antheridia  present  on  about  half  the  oogonia,  arising  from  just  below 

the  oogonium ;  eggs  I  or  2 . A.  spinosa  (p.  138) 

Antheridia  absent . A.  cornuta  (5) 

Sub-genus  Euachlya:  Eggs  eccentric,  with  a  large  oil  drop  on  the  periphery  outside  of 
the  protoplasm,  or  subcentric,  with  the  protoplasm  nearer  one  side  than  the  other 
and  surrounded  or  nearly  so  by  small  droplets  of  oil.  Antheridial  branches  androgy¬ 
nous  or  diclinous,  usually  branched  and  often  long;  antheridia  elongated,  their  sides 
applied  to  the  oogonia;  often  branched.  Oogonial  walls  hyaline  or  rarely  yellowish. 
Sporangia  typically  narrowed  toward  the  tip;  spores  with  a  strong  tendency  to  form 
a  hollow  sphere  on  emerging. 

Prolifera  Group :  Eggs  eccentric  with  a  single  large  oil  drop  on  one  side 

Antheridia  present;  oogonial  wall  normally  without  papillae  or  warts 

Antheridia  practically  all  androgynous;  present  on  all  or  a  majority  of  the 
oogonia;  eggs  usually  more  than  two 

Antheridia  on  all  oogonia,  arising  mainly  from  the  main  hyphae,  but 
also  at  times  from  the  very  short  oogonial  stalk;  oogonial  wall  hyaline, 

pitted  but  the  pits  not  very  conspicuous . A.  americana  (6) 

Antheridia  on  all  oogonia,  nearly  always  arising  from  the  main  hyphae; 
oogonial  wall  yellow,  with  very  conspicuous  pits;  oogonial  stalk  about 
as  long  as  the  diameter  of  the  oogonium;  eggs  23-26^  thick 

A.  americana  var.  cambrica  (p.  139) 
Antheridia  on  all  oogonia,  arising  only  from  the  main  hyphae;  oogonial 
walls  unpitted,  their  stalks  one  to  three  times  as  long  as  the  oogonial 

diameter;  eggs  18-25/i  thick . A.  deBaryana  (p.  141) 

Antheridia  practically  all  androgynous,  present  on  about  75%  of  the  oogonia; 

eggs  usually  1  or  2,  mostly  33-36^  thick . A.  Orion  (7) 

Antheridia  always  diclinous  or  both  diclinous  and  androgynous,  usually 
longer  and  more  branched  than  in  the  above  four  species;  present  on  all  or 
nearly  all  the  oogonia;  eggs  usually  more  than  two 
Oogonial  wall  pitted 

Antheridial  branches  always  diclinous,  much  branched  and  winding 
like  a  parasite  about  the  oogonia;  eggs  small  (20-26^1),  numerous 

A.  prolifera  (p.  143) 

Like  the  above,  but  eggs  larger  (24-3 1.5/i)  and  spores  said  to  be 

without  a  swimming  stage . A.  aplanes  (p.143) 

Antheridial  branches  mostly  diclinous,  in  many  cases  winding  them¬ 
selves  about  the  main  hyphae;  eggs  18-24^  thick 

A.  proliferoides  (8) 

Antheridia  more  often  diclinous  than  androgynous,  not  winding 
about  the  hyphae  and  never  arising  from  the  oogonial  stalks; 

eggs  about  26-35/x  thick . A.  flagellata  (9) 

Antheridial  branches  about  equally  androgynous  and  diclinous, 
usually  long  and  much  branched  but  not  winding  about  the 
hyphae,  not  rarely  arising  from  the  oogonial  stalks;  eggs  17-23^ 

thick  . A.  imperfecta  (10) 

Oogonial  wall  unpitted  (except  in  one  case  in  certain  chemicals);  anther¬ 
idia  nearly  all  diclinous . A.  Klebsiana  (11) 


100 


THE  SAPROLEGNIACEAE 


Antheridia  absent;  eggs  usually  I  or  2;  oogonia  smooth  or  with  a  few  papillate 

outgrowths . A.  caroliniana  (12) 

Apiculata  Group:  Eggs  in  all  American  species  not  filling  the  oogonium  and  often  far 
from  filling  it,  subcentric,  with  one  or  more  rows  of  inconspicuous  droplets  all 
or  most  of  the  way  around  the  globule  of  protoplasm  which  is  nearer  one  side 
than  the  other;*  oogonial  wall  unpitted  except  in  A.  conspicua 
Eggs  few  (usually  1-5),  most  about  36^  thick;  oogonia  often  with  an  apiculus; 

antheridia  in  greater  part  androgynous . A.  apiculata  (13) 

Eggs  few  (usually  1  or  2),  most  about  45/u  thick;  otherwise  as  in  A.  apiculata 

A.  apiculata  var.  prolifica  (14) 

Eggs  usually  4-6,  about  45^  thick;  oogonium  without  an  apiculus 

A.  megasperma  (15) 

Eggs  more  numerous  and  smaller 

Oogonia  smooth,  antheridia  androgynous . A.  polyandra  (16) 

Oogonia  smooth,  antheridia  both  androgynous  and  diclinous 

A.  conspicua  (17) 

Oogonia  smooth,  antheridia  diclinous 

Oogonia  subspherical  to  short  pyriform,  their  stalks  long 

A.  oblongata  (18) 

Oogonia  spherical,  their  stalks  short . A.  oblongata  var.  globosa  (19) 

Oogonia  papillate;  antheridia  diclinous  and  androgynous 

Oogonia  with  1-10  papillate  projections;  eggs  usually  4-8 

A.  oligacantha  (p.  144) 

Oogonia  with  more  numerous  papillate  projections;  eggs  usually  about  10 

A.  recurva  (p.  144) 

Sub-genus  Glomeroachlya:  Oogonia  often  borne  in  branched  glomeruli,  very  small, 
their  unpitted  walls  thickly  covered  with  blunt  warts;  eggs  single,  eccentric;  antheridial 
branches  androgynous  and  arising  near  the  oogonium,  but  at  times  a  little  branched; 
antheridia  as  in  Centroachlya.  There  is  but  one  species  in  the  sub-genus. 

A.  glomerata  (20) 

Sub-genus  Thraustoachlya:  Eggs  eccentric  with  a  single  large  oil  drop  outside  of  the 
protoplasm  at  full  maturity.  Antheridia  all  diclinous  and  present  on  all  oogonia. 
Oogonial  wall  yellowish.  Sporangia  often  releasing  the  spores  by  disintegration  as  in 


Thraustotheca.  There  is  but  one  species  in  the  sub-genus . A.  dubia  (21) 

Position  doubtful;  oogonia  absent . Achlya  sp.  (22) 

Artificial  key  to  the  Species  of  Achlya f 

1.  Oogonia  absent . Achlya  sp.  (22) 

I.  Oogonia  without  spines  or  papillate  outgrowths  or  only  a  few  of  them  with  such  pro¬ 
jections  . 2 

1.  Oogonia  mostly  with  spines  or  papillate  outgrowths . II 

2.  Antheridial  branches  almost  always  androgynous . 3 

2.  Antheridial  branches  diclinous  or  both  diclinous  and  androgynous . 6 


*  The  exact  structure  of  the  eggs  in  A.  oligacantha  and  A.  polyandra  is  not  known.  The 
eggs  of  the  first  ate  described  as  “centric”  by  deBary  and  those  of  A. gracilipes,  which  may  be 
the  same  as  the  second,  he  also  describes  as  centric,  and  we  have  no  data  on  the  egg  structure 
of  A.  recurva.  Other  characters,  however,  point  to  their  inclusion  here. 

f  American  species  are  followed  by  a  number;  European  by  a  page  reference. 


ACHLYA 


IOI 


3.  Eggs  small,  averaging  less  than  2 3//  in  diameter  . 4 

3.  Eggs  larger,  averaging  more  than  23//  in  diameter . 5 

4.  Oogonial  walls  pitted;  antheridial  branches  arising  from  the  main  hyphae  between  and 

near  the  oogonial  branches . A.  americana  (6) 

4.  Oogonial  walls  unpitted  (except  where  the  anlheridia  touch) ;  antheridial  branches 
arising  from  the  oogonial  branches,  sometimes  from  the  base  of  the  oogonium;  eggs 
centric . A.  racemosa  (2) 

4.  Oogonial  branches  not  long,  oogonial  wall  unpitted;  eggs  eccentric,  about  18-25// 

thick,  usually  3-10;  antheridial  branches  rather  long  and  branched,  arising  as  a  rule 
from  the  main  hyphae  (rarely  from  the  oogonial  stalks  also) ;  antheridia  on  all  oogonia 

A.  deBaryana  (p.  141) 

5.  Oogonial  branches  about  as  long  to  twice  as  long  as  the  diameter  of  the  oogonia  or  some 

even  longer;  oogonial  wall  strongly  pitted;  most  eggs  about  25//  thick;  antheridia 

on  all  or  nearly  all  oogonia . A.  conspicua  (17) 

5.  Oogonial  branches  much  longer  than  the  diameter  of  the  oogonia;  oogonial  wall  unpitted ; 
eggs  subcentric  (?),  about  27//  thick,  5  to  25  in  an  oogonium;  antheridia  on  all  oogonia 
from  branches  which  arise  as  a  rule  from  the  oogonial  stalk.... A.  polyandra  (16) 

5.  Oogonial  branches  much  longer  than  the  diameter  of  the  oogonia;  oogonial  wall  un¬ 

pitted;  eggs  eccentric,  usually  1-2  in  an  oogonium,  most  about  33-36//  thick 

A.  Orion  (7) 

6.  Oogonial  wall  pitted . 7 

6.  Oogonial  wall  unpitted  (except  in  one  case  in  certain  chemicals) . 9 

7.  Antheridial  branches  always  diclinous,  much  branched  and  winding  like  a  parasite 

about  the  oogonia;  eggs  small  (20-26//),  numerous . A.  prolifera  (143) 

7.  Like  the  above,  but  eggs  larger  (24-31.5//)  and  spores  said  to  be  without  a  swimming 
stage . A.  aplanes  (p.  143) 

7.  Antheridial  branches  diclinous  and  androgynous . 8 

8.  Antheridial  branches  mostly  diclinous,  in  many  cases  winding  themselves  about  the 

main  hyphae . A.  proliferoides  (8) 

8.  Antheridia  more  often  diclinous  than  androgynous,  not  winding  about  the  hyphae  and 
never  arising  from  the  oogonial  stalks . A.  flagellata  (9) 

8.  Antheridial  branches  about  equally  androgynous  and  diclinous,  usually  long  and  much 

branched  but  not  winding  about  the  hyphae,  not  rarely  arising  from  the  oogonial 
stalks . A.  imperfecta  (10) 

9.  Antheridial  branches  all  diclinous;  oogonial  wall  unpitted;  eggs  numerous . 10 

9.  Antheridial  branches  all  diclinous;  oogonial  wall  unpitted;  eggs  few;  sporangial  wall 

often  disintegrating . A.  dubia  (21) 

9.  Antheridial  branches  mostly  androgynous;  eggs  2-8 . A.  megasperma  (15) 

10.  Oogonia  oval  to  pyriform  (in  a  variety  globular);  eggs  numerous,  usually  about  15, 

averaging  23//  thick  (27 //  in  Humphrey’s  form) . A.  oblongata  (18) 

10.  Oogonia  round,  their  stalks  short;  eggs  averaging  10-15  in  an  oogonium,  and  27/4  thick 

A.  oblongata  var.  globosa  (19) 

10.  Oogonia  round  or  slightly  oval,  the  stalks  short;  eggs  4-10  in  an  oogonium,  averaging 


about  25// thick . . . A.  Klebsiana  (11) 

1 1.  Oogonia  without  antheridia . 12 

11.  Oogonia  (at  least  in  part)  with  antheridia . 13 

12.  Oogonia  spherical  or  elliptical;  eggs  1-4,  about  29//  thick . A.  cornuta  (5) 

12.  Oogonia  oval;  eggs  numerous,  generally  about  20,  averaging  20/z  thick;  parasitic  on 

fish . A.  Hoferi  (p.  145) 

12.  Oogonia  spherical;  eggs  few,  usually  1-2,  not  rarely  4,  22//  thick. . .  .A.  caroliniana  (12) 


102 


THE  SAPROLEGN I  AC  E  AE 


13.  Antheridia  both  androgynous  and  diclinous;  oogonia  with  a  single  apiculus;  eggs  1-5 

in  an  oogonium,  large,  averaging  about  36/*  thick  . A.  apiculata  (13) 

13.  As  in  A.  apiculata  except  eggs  usually  1-2  and  oogonia  smaller 

A.  apiculata  var.  prolifica  (14) 
13.  Antheridia  both  androgynous  and  diclinous,  oogonia  usually  with  several  blunt  papillae; 
eggs  4-8  (seldom  up  to  12  or  more)  in  an  oogonium,  small  (15-25/*) 

A.  oligacantha  (p.  144) 

13.  As  above,  but  eggs  usually  about  10  (1-25),  22-27/*  thick;  papillae  more  numerous, 


and  oogonial  stalks  recurved  above . *4.  recurva  (p.  144) 

13.  Antheridia  all  or  almost  all  androgynous . 14 

14.  Antheridia  often  arising  from  a  hypogynal  cell;  eggs  commonly  3-5  in  an  oogonium, 

averaging  27-28/*  thick . A.  hypogyna  (1) 

14.  Antheridia  not  formed  as  above . 15 

15.  Eggs  commonly  one  or  rarely  two  or  three  in  an  oogonium . 16 

15.  Eggs  commonly  4-6  in  an  oogonium,  averaging  25/*  thick . A.  papillosa  (4) 

15.  Eggs  commonly  1-4  in  an  oogonium  averaging  30-37/*  thick . A.  colorata  (3) 

16.  Oogonium  densely  covered  with  sharp  spines;  eggs  one,  rarely  two  or  three,  commonly 

34-36.5/*  thick . A.  radiosa  (p.  139) 

16.  Oogonia  covered  with  sharp  or  blunt  spines,  mostly  barrel-shaped  with  a  large  apical 

point . A.  spinosa  (p.  138) 

16.  Oogonia  covered  with  blunt  warts,  roughly  spherical  and  with  a  distinct  point;  eggs 
one  or  rarely  two,  averaging  about  20 /*  thick . A.  glomerata  (20) 


i.  Achlya  hypogyna  Coker  and  Pemberton.  Bot.  Gaz.  45:  194,  figs. 

1-6.  1908. 

Plates  29  and  30 

Hyphae  slender,  tapering  gradually  toward  the  apex,  at  base  about 
35p.  in  diameter,  at  or  near  tip  about  8[o.,  in  vigorous  cultures  reaching 
a  length  of  1  cm.  Sporangia  rather  plentiful  or  few,  nearly  cylindrical, 
a  little  larger  at  the  rounded  and  papillate  distal  end,  usually  curved, 
somewhat  like  those  of  Protoachlya  paradoxa ;  dictiosporangia  common, 
sometimes  more  abundant  than  the  typical  sort;  spores  on  emerging 
ciliated,  a  part  usually  dropping  to  the  bottom  and  showing  a  little  mo¬ 
tion  from  the  sluggish  cilia.  Gemmae  at  times  abundant,  again  few, 
pyriform  or  flask-shaped,  less  often  spherical,  often  in  chains  of  two, 
three  or  four;  long,  rod-shaped  gemmae  are  also  formed  by  segmenta¬ 
tion  of  the  hyphae.  Oogonia  generally  borne  on  short  branches,  race- 
mosely  arranged  on  the  main  hyphae,  but  occasionally  terminating  a 
main  hypha,  and  very  rarely  intercalary;  globular  or  rarely  oblong,  the 
walls  not  pitted,  more  or  less  abundantly  producing  short  or  long  rounded 
outgrowths,  or  a  varying  proportion  smooth;  yellow  when  old;  diameter 
26-8310.  without  the  papillae  which  are  up  to  30^  long,  the  longest  at 
times  on  the  smallest  oogonia.  Eggs  1-7  (commonly  3-5),  centric, 
diameter  20-3610.,  averaging  27-28(0.;  not  rarely  elliptic  and  then  up  to 
45  X  5710..  Antheridia  cut  off  from  oogonial  branches  just  below  the 
oogonia,  very  rarely  absent;  simple  antheridial  branches  with  one  or 


PLATE  29 


PLATE  29 
Achlya  hypogyna 

Fig.  i.  Oogonium  with  apical  papillae  and  single  egg.  X  503. 

Fig.  2.  Oogonium  with  papillae  on  side  of  wall.  X  503. 

Fig.  3.  Oogonium  with  a  dictiosporangium  attached  to  it.  X  503. 

Fig.  4.  Sporangium  emptying,  the  spores  with  cilia.  X  503. 

Fig.  5.  Intercalary  oogonium  with  single  egg  and  many  papillae.  X  503. 

Fig.  6.  Gemmae.  X  278. 

Fig.  7.  Sporangia.  X  188. 

Fig.  8.  A  dictiosporangium.  X  503. 

Fig.  9.  Apical  oogonium  with  basal  antheridium  and  egg  with  no  definite  wall  yet  formed. 
X  503- 

Fig.  10.  Smooth  oogonium  with  egg  as  in  9.  X  503. 

Fig  11.  Oogonium  with  diclinous  antheridium.  X  503. 


PLATE  29 


ACHLYA  HYPOGYNA. 


PLATE  30 


PLATE  30 
Achlya  hypogyna 

Fig.  i.  Gemmae  and  sporangium.  X  167. 

Fig.  2.  Gemmae.  X  247. 

Fig.  3.  Two  empty  sporangia,  one  with  an  internal  proliferation  that  is  bearing  an  oogo¬ 
nium  on  its  tip  which  is  just  outside  the  sporangium.  X  247. 

Fig.  4.  A  small  oogonium  with  two  fertilizing  tubes.  X  247. 

Fig.  5.  Habit  of  sporangia.  X  167. 

Fig.  6.  Oogonium  with  a  hypogynous  antheridium  and  another  of  more  distant  origin. 
X  447- 

Fig.  7.  Small  immature  oogonium  covered  with  long  papillae.  X  447- 

Fig.  8.  Oogonium  with  hypogynous  and  lateral  antheridia.  X  247. 

Fig.  9.  Oogonium  with  an  intercalary  basal  antheridium.  X  447. 

Fig.  10.  Intercalary  oogonium  without  antheridia  but  with  a  thick-walled  ingrowth  from 
one  end.  X  247. 

Fig.  1 1.  An  oogonium  with  ripe  eggs,  and  showing  a  hypogynous  antheridium  with  a  lateral 
branch;  also  antheridia  of  more  distant  origin.  One  of  the  latter  with  its 
fertilizing  tubes  pulled  out  by  tension  in  mounting.  X  447- 

Fig.  12.  Oogonium  with  a  stout  papilla.  X  447. 

Fig.  13.  A  typical  oogonium  and  antheridium.  X  447. 


PLATE  30 


ACHLYA  HYPOGYNA 


ACHLYA 


I03 

more  branched,  tuberous,  antheridia  also  present  at  times  and  arising 
from  the  suboogonial  cell  or  below  it  or  even  from  the  main  hypha;  in 
the  latter  case  rarely  diclinous.  Fertilizing  tubes  arising  through  the 
common  septa  from  the  suboogonial  cell  and  penetrating  the  oogonia 
from  below  (hypogynous),  also  from  the  other  antheridia  when  present. 

Compared  with  other  species  it  may  be  said  to  have  medium  occur¬ 
rence,  appearing  mostly  in  fall  in  such  places  as  brook  south  of  athletic 
field,  Arboretum  branch,  branch  on  south  edge  of  Glen  Burnie  meadow. 

An  extremely  variable  plant.  The  smallest  or  largest  oogonia  may 
be  quite  smooth  or  heavily  spined  or  with  every  possible  variation  be¬ 
tween;  they  may  be  quite  free  of  antheridial  cells  or  branches  or  either 
or  both  may  be  present,  and  all  these  different  conditions  may  be  found 
in  a  single  culture  on  ordinary  media,  as  a  mushroom  grub  or  gnat. 

The  presence  of  a  hypogynous  antheridial  cell  and  the  origin  of  the 
fertilizing  tubes  from  the  septa  separating  this  cell  from  the  oogonium 
distinguish  this  from  all  other  species  of  Saprolegniaceae  except  the 
Ilypogyna  group  in  Saprolegnia.  It  is  hardly  probable  that  the  presence 
of  a  hypogynous  cell  is  anything  more  than  an  adventitious  resemblance 
to  S.  hypogyna.  In  other  essential  points  the  two  species  are  very  dif¬ 
ferent.  In  the  latter  the  oogonia  are  borne  in  long  chains  or  are  inter¬ 
calary  and  their  walls  are  strongly  pitted;  the  sporangia  are  of  different 
shape  and  proliferate  abundantly  internally,  and  the  spores  all  swarm 
at  once.  It  is  evident  that  Achlya  hypogyna  is  related  to  Achlya  color ata 
and  A.  racemosa.  The  general  habit,  the  structure  of  the  oogonia,  and 
the  sub-oogonial  antheridia  are  very  much  the  same  as  in  A.  colorata; 
but  the  slender  hyphae,  the  hypogynal  cell,  colorless  oogonial  walls, 
and  the  smaller  eggs  easily  distinguish  the  present  species. 

Maurizio  suggests  that  sub-oogonial  antheridia  with  hypogynous 
tubes  may  be  of  generic  value  in  Saprolegnia  (1899),  but  such  a  suggestion 
can  scarcely  be  followed  when  we  find  this  character  present  in  only 
one  of  a  group  of  related  forms,  not  to  mention  the  variability  of  that 
character  in  S.  hypogyna  itself. 

In  a  very  few  cases  the  oogonia  are  oblong  and  some  intercalary 
ones  are  occasionally  seen.  When  the  stalk  is  very  short  the  anther- 
idium  may  extend  some  distance  into  the  main  hypha.  Oogonia  with 
smooth  walls  are  usually  very  few  or  none  on  ordinary  media;  occasionally, 
however,  a  culture  on  insects  in  water  may  contain  a  good  many  such. 

Maurizio  (Flora  79:  149.  1894)  and  Kauffman  (Ann.  Bot.  22:  382. 
1908)  think  that  the  fertilizing  tube  in  Saprolegnia  hypogyna  is  not  such, 
“but  represents  a  tendency  to  produce  secondary  growth,  as  in  spor¬ 
angia.”  It  is  important  to  note  in  this  connection  that  there  are  two 
kinds  of  growths  into  the  oogonium.  One  kind  is  thin-walled  and  full 


104 


THE  SAPROLEGNIACEAE 


of  protoplasm  and  comes  only  from  the  true  antheridial  cell  either  below 
or  on  lateral  stalks;  the  other  is  thick- walled  and  knotted  and  very  soon 
without  protoplasm  and  grows  in  from  below  only  when  no  antheridial 
cell  is  cut  off.  This  is  exactly  like  the  tubes  that  enter  so  often  the 
oogonia  in  the  Ferax  group  in  Saprolegnia  and  the  Prolifer  a  group  in 
Achlya.  The  last  kind  is  certainly  functionless;  while  the  first-mentioned 
are  probably  functional. 

The  following  20  observations  were  made  on  cultures  from  No.  2 

! 

of  September  10,  1912: 

On  ant  in  rain  water.  Sporangium  seen  to  discharge  at  10:55.  Spores  emerged  rapidly, 
and  expanded  into  an  open  cluster.  All  the  more  distant  ones  fell  away  and  dropped 
at  once  to  the  bottom,  at  rest,  where  they  lay  in  an  open  cluster,  some  at  a  distance 
from  others,  some  in  contact.  The  other  half  remained  attached  to  tip  of  sporangium 
in  an  irregular,  apparently  solid,  mass.  There  was  no  motion,  except  at  very  moment 
of  escape,  when  the  separate  ones  on  periphery  were  seen  to  rock  a  little.  The  spores 
were  watched,  and  they  began  to  emerge  from  their  cysts  at  1  :(>5,  showing  a  rest  of 
2  hours  and  10  minutes. 

On  egg  yolk  in  distilled  water.  Spores  emerged  rapidly,  and  behaved  exactly  as  described 
in  preceding  experiment,  except  that  about  of  the  spores  fell  at  once  to  bottom,  and 
that  there  was  a  very  obvious  movement  in  all  the  spores  that  could  be  seen  individ¬ 
ually.  This  movement  consisted  in  a  rocking  and  slight  change  of  place  and  readjust¬ 
ment.  This  lasted  only  a  few  seconds. 

On  egg  yolk  in  .1  %  Ca3(P04)2.  Three  sporangia  were  seen  to  discharge.  Two  dropped 
all  spores  to  bottom,  and  slight  swimming  movements  were  noticeable  in  outer  ones. 
One  sporangium  was  put  on  glass  slide  and  then  discharged.  The  spores  spread  at 
once  in  a  loose  colony,  and  most  of  them  showed  a  decided  rocking  and  change  of  place, 
far  more  plain  than  in  the  other  cases.  They  could  readily  be  watched  in  the  very 
shallow  water,  and  their  movement  was  unmistakable. 

In  nearly  sterile  pea  broth.  Grew  beautifully  through  the  broth  and  formed  a  dense  mat 
on  the  surface.  In  this  mat  were  formed  many  normal  oogonia.  None  were  formed 
below  the  mat.  This  culture  was  transferred  from  the  test  tube  in  which  it  was  origin¬ 
ally  made  to  a  petri  dish  and  more  pea  broth  added.  Soon  the  whole  mycelium  was 
plentifully  dotted  with  oogonia  that  were  quite  healthy  though  bacteria  had  by  this 
time  become  abundant.  The  great  majority  of  the  oogonia  were  either  with  hypog- 
ynous  antheridia  or  none,  but  several  were  found  with  antheridia  coming  from  a  dis¬ 
tance,  as  in  figs.  6  and  11,  pi.  30. 

On  corn  meal  agar.  Extensive  growth.  Many  gemmae  and  very  many  oogonia.  These 
were  larger  than  usual  and  less  spiny.  About  half  contained  3,  4  or  6  eggs,  while  in 
other  conditions,  such  as  on  ants  and  in  pea  broth,  a  great  majority  contained  only  one 
or  two  eggs.  No  antheridia  were  present,  and  the  spines  were  very  much  reduced. 
No  inflated  or  abnormal  oogonia. 

In  pea  broth.  Good  growth,  but  did  not  fill  dish.  Many  normal  sporangia,  and  very 
many  oogonia,  these  quite  spiny  and  the  vast  majority  with  only  one  or  two  eggs 
No  antheridia  seen.  The  only  resting  bodies  seemed  to  be  arrested  oogonia. 

In  maltose  5%  peptone  .01%.  Vigorous  growth,  filling  dish.  Many  inflated  oogonia, 
some  without  spines,  but  irregular  in  outline.  No  good  eggs  and  no  antheridial  tubes. 
No  sporangia  or  gemmae.  Protoplasm  of  the  hyphae  became  segregated  into  dense 
little  bits  at  intervals.  Most  of  the  oogonia  have  good  long  spines.  A  part  of  this 


ACHLYA 


I05 


culture  was  put  in  fresh  maltose-peptone  to  see  if  the  bits  of  protoplasm  were  alive. 
No  growth  resulted. 

On  corn  meal,  egg  yolk  agar.  Growth  very  vigorous,  soon  covering  the  dish  and  many 
long  aerial  hvphae  reaching  cover  (A4  inch  or  more  long).  Very  abundant  oogonia 
with  hypogynal  tube  nearly  always  present,  but  not  more  than  5%  with  antheridial 
cell  cut  off.  Spines  reduced  to  low  prominences  and  angles  in  nearly  all  cases.  No 
other  reproduction. 

The  following  six  cultures  were  on  lumps  of  egg  yolk  in  distilled 
water  with  the  salt  added : 

In  .1%  KNO3.  Growth  vigorous.  No  sporangia  visible.  Many  oogonia,  not  more  than 
half  maturing  eggs.  A  good  many  intercalary.  Sub-oogonial  antheridial  cell  not 
cut  off  in  more  than  ]4,  cases,  and  no  antheridial  tubes  seen.  One  case  was  seen  of  a 
diclinous  antheridium. 

In  .1%  KH2PO4.  Growth  vigorous.  Many  sporangia,  discharging  normally.  Many 
oogonia,  only  a  small  number  maturing  eggs,  Antheridial  cell  cut  off  below  in  great 
majority  of  cases,  but  no  tubes  formed.  About  14  cases  seen  of  outside  antheridial 
branches  with  club-shaped  antheridia,  nearly  all  diclinous.  This  shows  the  effect  of 
this  salt  in  antheridial  formation. 

In  .1%  NaHjPO*.  Growth  vigorous.  A  moderate  number  of  sporangia,  discharging 
normally.  Many  oogonia,  very  few  maturing  eggs,  and  almost  no  antheridial  cells. 

In  .1%  K2SO4.  Growth  vigorous.  A  few  sporangia.  Many  oogonia  and  a  good  many 
good  eggs.  Antheridial  cells  cut  off  in  scarcely  half  the  cases,  but  hypogynal  tubes 
present  in  most  cases  where  there  were  antheridial  cells.  Several  cases  seen  of  outside 
antheridial  branches. 

In  .1%  Ca3(P04)2.  Growth  vigorous.  Many  sporangia.  In  discharging  about  ) 2  scatter 
away  from  the  tip  with  very  obvious  swimming  motion,  but  slowly,  and  fall  in  an  open 
group.  A  drop  of  iodine  on  an  emerging  group  of  spores  showed  the  cilia  clearly  at 
the  tip  (pi.  29,  fig.  4).  Many  oogonia,  about  one-third  with  good  eggs,  and  these 
mostly  with  antheridial  cell  cut  off  and  with  hypogynal  tube.  The  most  singular  thing 
about  this  culture  is  the  occurrence  frequently  of  rows  of  long  eggs  in  sections  of  hyphae 
which  might  be  continuations  of  an  oogonial  cavity  or  might  not.  That  is,  long  sec¬ 
tions  of  the  hyphae  are  cut  off  as  oogonia  and  these  are  quite  smooth,—  not  spiny  like 
ordinary  oogonia. 

In  1%  K3PO4.  Slight  growth.  A  good  many  inflated  and  abnormal  oogonia  without 
eggs  or  antheridial  cells. 

The  following  six  cultures  were  made  on  lumps  of  egg  agar  in  distilled 
water  with  the  medium  added  (infected  from  pure  spore  culture  on 
corn  meal  agar) : 

In  .1%  KNO3.  Vigorous  growth.  Many  oogonia,  hardly  half  with  antheridial  cells,  and 
many  of  the  latter  with  antheridial  tubes.  Out  of  more  than  1000  examined  9  had 
antheridia  from  outside,  most  of  them  androgynous.  Oogonia  normally  spiny.  No 
■  sporangia  to  be  seen. 

In  .1%  KH2PO4.  Vigorous  growth.  Many  normal  sporangia  and  many  normal  oogonia; 
antheridial  cell  and  hypogynous  tube  nearly  always  present.  At  least  5%  of  the 
oogonia  with  additional  external  antheridia  which  are  either  androgynous  or  diclinous. 

In  .1%  NaH2P04.  Vigorous  growth.  Many  normal  sporangia.  Three  sporangia  were 
observed  while  discharging.  The  spores  were  killed  on  slide  and  all  showed  cilia  very 
plainly,  both  in  and  out  of  sporangium.  Distinct  swimming  noticed  before  killing. 


THE  SAPROLEGNIACEAE 


106 


Oogonia  abundant,  the  majority  with  antheridial  cells  and  tubes.  A  good  many,  not 
over  2%,  with  outside  antheridia. 

In  .1%  K2SO4.  Vigorous  growth.  Very  few  sporangia.  Many  oogonia,  nearly  all  with 
antheridial  cells  and  tubes  and  at  least  5%  with  extra  outside  antheridia. 

In  .1%  Ca3(P04)2.  Rather  sparse  growth.  Very  many  sporangia.  Many  oogonia,  a 
good  many  extending  into  the  threads,  which  also  contained  eggs.  Antheridial  cell 
cut  off  in  most  cases,  and  tube  formed.  Not  more  than  1  or  2%  of  outside  extra 
antheridia. 

In  .1%  K3PO4.  Growth  moderate.  No  sporangia.  Many  oogonia,  nearly  all  failing  to 
mature  eggs.  Antheridia  cut  off  on  only  a  small  number. 

The  following  two  experiments  were  made  to  test  the  best  method 
of  preserving  live  cultures: 

Culture  from  No.  2  of  September  10,  1912,  put  in  vial  on  corn  meal  agar  on  March  18,  1913. 
Found  to  be  dead  when  tested  on  December  1,  1913. 

Culture  on  corn  meal  agar  put  in  vial  of  water  which  was  then  closed  with  a  plug  of  cotton 
and  put  in  a  dark  place  in  May,  1913.  Test  for  life  was  made  with  a  mushroom  grub 
in  December,  1913,  and  new  growth  resulted.  The  eggs,  however,  were  nearly  all 
dead  and  disorganized.  Scarcely  one  in  100  was  alive. 

2.  Achlya  racemosa  Hildebrand.  Jahrb.  f.  wiss.  Bot.  6:249,  pi.  15.  1867. 
?  Achlya  lignicola  Hildb.  Jahrb.  f.  wiss.  Bot.  6:  255,  pi.  16,  figs. 
i-6a.  1867. 


Plates  14  and  31 

Hyphae  stout,  usually  25-36(0.  thick  at  base.  Sporangia  long,  almost 
cylindrical,  rounded  or  tapering  at  the  tips,  about  the  size  of  the  hyphae 
bearing  them  or  sometimes  slightly  larger,  sometimes  twisted  like  a  cork¬ 
screw.  Spores  9-1 1  [j.  in  diameter;  on  emerging  forming  an  irregular 
cluster  or  imperfect  sphere  which  slowly  expands  as  if  embedded  in 
jelly  so  that  the  spores  become  more  or  less  separated  singly  or  in  groups. 
Gemmae  usually  few,  formed  by  the  distal  parts  of  hyphae  becoming 
divided  into  joints  after  being  densely  filled  with  protoplasm.  Oogonia 
racemosely  borne  on  short  lateral  branches,  rarely  intercalary,  plentifully 
developed  in  all  cultures,  rather  small,  40-70(0.  in  diameter;  wall  dis¬ 
tinctly  yellowish  at  maturity,  smooth  and  unpitted  except  where  anther¬ 
idia  touch.  Eggs  variable  in  size,  16.6-27.7(0.  in  diameter,  most  about 
22p,  centric,  1-8  in  an  oogonium  (Humphrey  says  1-10),  in  most  cases 
2-5,  centric,  the  wall  thick  (about  3.510.).  Antheridial  branches  short,  arising 
from  oogonial  branches  near  the  basal  walls  of  the  oogonia,  or  as  often 
from  the  neck-shaped  base  of  the  oogonium  or  even  from  its  curved 
surface,  rarely  from  the  main  hyphae.  Antheridia  one  or  two,  some¬ 
times  more,  to  each  oogonium;  short-clavate,  usually  bent  and  applied 
by  their  tips  to  the  oogonia. 


PLATE  31 


PLATE  31 


Achlya  racemosa 

Fig.  i.  Habit  of  fruiting.  X  1 1 5. 

Fig.  2.  A  sporangial  cluster.  X  188. 

Fig.  3.  Gemmae.  X  122. 

Fig.  4.  Forms  of  sporangia.  X  188. 

Fig.  5.  Habit,  showing  part  of  a  sporangium  and  several  oogonia,  one  intercalary  and  of 
peculiar  shape,  another  with  a  diclinous  antheridium.  X  278. 

Fig.  6.  Two  apical  oogonia  on  the  same  hypha,  an  antheridium  arising  from  the  base  of 
one  and  going  to  the  other  oogonium.  X  503. 

Fig.  7.  Intercalary  oogonia.  X  503. 

Fig.  8.  An  oogonium  with  two  characteristic  antheridia  and  ripe  eggs.  X  503. 

Fig.  9.  An  oogonium  with  typical  antheridia.  X  503. 


PLATE  31 


mi 


ACHLYA  RACEMOSA 


ACHYLA 


l  07 

Not  rare  in  cool  or  cold  weather  in  springs,  branches,  and  edges  of 
marshes,  as  in  Arboretum  spring  and  branch,  and  in  Glen  Burnie  marsh. 
Collected  24  times  in  Chapel  Hill  between  February  15,  1912,  and  December 
15,  1913  (see  table  on  p.  14),  and  many  times  since.  Also  found  near  Yadkin 
College,  N.  C.,  by  Totten,  and  reported  from  Amherst,  Mass.,  by  Hum¬ 
phrey,  and  from  Washington  County,  Michigan,  by  Kauffman  (’15,  p. 
195).  For  other  illustrations  see  Cornu  (’72),  pb  F  figs.  2-8;  Humphrey 
(’92),  pi.  19,  figs.  92-95;  Pringsheim  (’73),  pi.  19,  figs.  1-15;  pi.  21,  figs. 
1,2,  13;  pi.  22,  figs.  1-3;  also  (’83a),  pi.  7,  figs.  10-20;  Zopf  (’84),  pi.  20, 
figs.  1-9  (oogonia  parasitized  by  Rhizidiomyces) ;  Petersen  (To),  fig.  3b 
Minden  (T 2),  fig.  2a  on  p.  520. 

Easily  distinguished  from  all  other  species,  except  A.  colorata,  A. 
spinosa  and  A.  radiosa,  by  the  position  and  behavior  of  the  antheridial 
branches,  and  remarkable  in  being  the  only  species  except  A.  colorata  in 
which  the  antheridial  branches  may  come  from  the  oogonia  themselves. 
Easily  distinguished  from  A.  colorata  by  the  always  smooth  oogonial 
wall,  and  by  the  much  smaller  eggs  which  reach  a  higher  number.  For 
experiments  with  this  species  in  various  media  see  Pieters  (’15b,  p.  529). 

Achlya  lignicola  is  considered  a  synonym  of  A.  racemosa  by  Fischer, 
Humphrey,  Minden,  and  others,  but  Hildebrand’s  (’67)careful  observations 
on  apparently  abundant  material  indicate  a  variety  that  we  will  call  var. 
lignicola  (Hildb.),  which  is  distinguished  by  the  more  slender  and  less 
branched  mycelium  (growing  on  wood) ;  and  by  the  smaller  oogonia  which 
are  borne  ordinarily  on  the  end  of  long  slender  hyphae,  less  often  on  short, 
lateral  branches,  but  even  then  not  racemosely  arranged. 

Hine  (’78)  describes  a  variety  (without  name,  p.  140,  pi.  6,  figs. 
1-14)  which  seems  to  differ  from  others  in  the  frequent  appearance  of 
cylindrical  intercalary  oogonia  with  a  single  row  of  eggs. 

Minden  treats  Achlya  colorata  as  a  variety  or  form  stelligera  of  A. 
racemosa,  and  adds  two  other  forms  of  his  own  (the  second  we  take  to  be 
a  form  of  A.  colorata ),  as  follows  (T 2,  p.  548): 

(a)  Forma  maxima. 

Oogonial  wall  smooth  or  very  seldom  with  a  single  projection;  up 
to  8  antheridia  and  12  eggs.  This  form,  in  its  large  number  of  antheridia, 
resembles  A.  lignicola. 

(b)  Forma  Pringsheimii. 

Oogonial  walls  very  thick  and  yellow-brown,  mostly  with  few  pro¬ 
jections  which  may  give  the  oogonia  an  angular  appearance;  oogonial 
stalk  often  very  short;  antheridial  branches  often  springing  from  the 
oogonia  themselves,  and  at  times  from  the  main  hyphae.  With  few, 
often  only  1-3  eggs. 


io8 


THE  SAPROLEGXIACEAE 


3.  Achlya  colorata  Pringsh.*  Sitzungsber.  der  Akad.  der  Wissensch.  zu 
Berlin,  1882,  p.  855,  pi.  14,  figs.  12,  15-31. 

Achlya  racemosa  var.  stelligera  Cornu.  Ann.  Sci.  Nat.  Bot.  15: 
22.  1872. 


Plate  32 

Hvphae  stout,  25-50:0.  in  diameter  at  base.  Sporangia  long,  almost 
cylindrical,  or  slightly  tapering  toward  the  end,  very  little  or  not  at  all 
larger  than  the  hyphae  bearing  them.  Spores  1 1  ;j.  in  diameter,  emerg¬ 
ing  and  behaving  as  in  A.  racemosa.  In  neither  species  is  any  spontane¬ 
ous  movement  shown  before  encystment.  Oogonia  varying  greatly  in 
size,  41-90(0.  in  diameter,  rarely  as  much  as  107:0.,  commonly  55-66:0., 
racemosely  borne  on  short  lateral  branches  and  also  at  times  on  the 
tips  of  main  branches;  the  yellow  walls  producing  short,  blunt  out¬ 
growths  in  varying  number  or  rarely  almost  smooth.  Eggs  mostly  1-4, 
rather  rarely  5  and  very  rarely  6,  26-39(0.  in  diameter,  mostly  about 
30-37:0.,  centric,  the  wall  very  thick.  Antheridial  branches  short,  arising 
from  the  oogonial  branches  near  the  basal  wall  of  the  oogonium,  and, 
as  in  the  typical  A.  racemosa ,  often  from  the  neck-shaped  base  of  the 
oogonium  itself,  rarely  from  the  main  hyphae.  Antheridia  1-4  on 
each  oogonium,  commonly  2.  short-clavate,  usually  bent  and  apply¬ 
ing  their  tips  to  the  oogonium.  Gemmae  formed  at  the  maturity  of 
the  culture  in  large  numbers.  They  are  scarcely  enlarged  sections  of 
hyphae  arranged  in  rows  of  rarely  over  5,  one  end  often  projecting 
to  one  side  below  the  partition  and  somewhat  thickened.  They  do 
not  form  all  the  way  to  the  substratum,  but  only  near  the  ends  of  the 
hyphae.  When  brought  into  fresh  water  they  sprout  by  tubes  or  be¬ 
come  sporangia. 

Not  rare  in  winter  and  spring  in  branches,  outlets  of  springs,  etc., 
as  in  Arboretum  spring  and  brook,  and  branch  by  Raleigh  road  beyond 
cemetery.  Collected  29  times  before  December  15,  1913  (see  table),  and 
many  times  since.  For  other  illustrations  see  Pringsheim  (’73),  pi.  19,  figs. 
1— 1 5 ;  pi.  21,  figs.  1-3  and  13;  pi.  22,  figs.  1-3;  Pringsheim  (’83a)  pi.  7,  figs. 
10-20;  Hine  (’78),  pi.  6,  figs.  1-14;  Humphrey  (’92),  pi.  19,  figs.  96-98; 
Petersen  (’10),  fig.  3d. 

This  good  species  has  been  masquerading  since  its  first  discovery 
as  a  variety  or  form  of  A.  racemosa ,  and  Fischer  (Rabenhorst’s  Flora, 
p.  351),  finding  papillate  and  smooth  oogonia  on  the  same  thread,  con¬ 
siders  it  the  same  as  A.  racemosa.  It  is  true  that  smooth  or  nearly 
smooth  oogonia  may  appear  rarely  in  this  species,  but  they  are  not  the 
oogonia  of  A.  racemosa,  which  are  always  easily  recognized  by  their 
much  smaller  eggs.  We  have  never  seen  a  perfectly  smooth  oogonium 

*This  name  was  first  used  by  Pringsheim  in  a  footnote  in  1874  (Jahrb.  f.  wiss.  Bot. 
9:  205)  as  a  name  he  was  using  in  his  notes.  In  the  body  of  the  paper  and  in  the  plates 
he  still  uses  A.  racemosa. 


PLATE  32 


PLATE  32 
Achlya  colorata 

Fig.  I.  Habit  of  fruiting.  X  1 15. 

Fig.  2.  Sporangia,  one  with  spores  sprouting  as  in  Aplanes  (aplanosporangium).  X  1 1 5. 
Fig.  3.  Oogonium  with  four  antheridia.  X  503. 

Fig.  4.  Oogonium  with  antheridia  arising  from  the  oogonial  wall.  X  503. 

Fig.  5.  Gemmae  sprouting  to  filaments.  X  113. 

Fig.  6.  Enlarged  tip  of  sporangium  showing  spores  shrunken  about  iop,  away  from  wall 
before  escaping.  Showing  that  there  is  pressure  from  gelatinization  of  inner 
part  of  sporangial  wall.  X  810. 

Fig.  7.  Oogonium  with  ripe  eggs  and  two  antheridia,  one  arising  from  the  oogonial  wall. 

x  503- 


PLATE  32 


ACHLYA  COLORATA. 


ACHLYA 


109 


in  A.  color ata  or  a  papillate  one  in  A.  racemosa.  It  is  easily  distinguished 
from  the  typical  A.  racemosa  by  the  oogonia  bearing  short  blunt  out¬ 
growths  and  by  the  fewer  and  larger  eggs,  which  are  rarely  more  than 
live  to  an  oogonium.  As  in  Isoachlya  anispora  the  color  in  the  oogonial 
walls  becomes  much  fainter  after  repeated  culture  renewals.  Both  dictio- 
and  aplanosporangia  occur. 

On  mushroom  grub  in  distilled  water.  Showed  a  great  many  oogonia  (probably  A  of  all) 
with  antheridia  arising  from  the  oogonial  neck  (No.  6  of  Nov.  15,  1913). 

On  corn  meal  agar.  Growth  normal  but  delicate;  oogonia  not  abundant,  eggs  maturing  or 
going  to  pieces;  antheridia  absent  lrom  some  oogonia;  papillae  irregularly  produced 
and  on  some  oogonia  only  a  few  in  a  group  on  one  side  (No.  4  of  Feb.  14,  1918). 

Experiment  to  test  best  method  of  preserving  live  cultures: 

Culture  put  in  aquarium  jar  with  algae  in  laboratory  on  Ma>  17,  1911.  When  tested  on 
Septembei  22,  1917,  no  growth  occurred. 


4  Achlya  papillosa  Humphrey.  Trans.  Amer.  Phil.  Soc.  17:  125,  pi. 

20,  figs.  99-102.  1892  [1893]. 

We  have  not  found  this  and  its  relationship  must  be  considered 
doubtful.  The  following  is  from  Humphrey: 

“  Hyphae  rather  slender,  long.  Zoosporangia  sparingly  developed, 
cylindrical,  little  larger  than  the  hyphae.  Oogonia  terminal  on  main 
threads  or  on  short  lateral  branches,  or  sometimes  intercalary,  oval  or 
ovate,  rarely  globular,  thickly  studded  with  short,  blunt,  wart-like  out¬ 
growths  of  their  unpitted  walls,  often  with  a  marked  apiculus.  An- 
theridial  branches  usually  developed  with  each  oogonium,  fine  and 
branching,  arising  near  it  from  the  main  thread,  or  rarely  from  the  oogon¬ 
ial  branch.  Antheridia  imperfectly  formed.  Oospores  as  many  as 
twelve  in  an  oogonium,  oftenest  four  to  six,  centric,  their  average  diam¬ 
eter  about  251X. 

Massachusetts — Amherst. 

“This  plant,  which  seems  to  be  sufficiently  distinct  from  previously 
described  species,  has  been  obtained  in  several  cultures,  but  from  only 
a  single  source;  namely,  the  very  prolific  mossy  pool  in  Amherst,  already 
mentioned.  It  may  be  recognized  by  its  long  hyphae,  finer  than  those 
of  most  Achlyae,  and  its  oogonia  with  warty,  rather  than  spiny,  walls, 
and  several  oospores  in  each.  I  have  never  seen  well-differentiated 
antheridia  or  fertilization-tubes,  although  the  ends  of  the  antheridial 
branches  are  applied  to  the  oogonia. 

“While  bearing  no  near  resemblance  to  any  species  heretofore  fig¬ 
ured,  this  plant  may  be  somewhat  closely  related  to  the  next  [A.  recurva 
Cornu],  if  the  latter  is  well  founded.” 


I  10 


THE  S  A  P  R0  L  EG  X I  AC  E  A  E 


5.  Achlya  cornuta  Archer.  Quart.  Jour.  Mic.  Sci.  7:  126,  pi.  6,  figs. 
2-6.  1867. 

?  Achlya  stellata  deBary.  Bot.  Zeit.  46:  648,  pi.  10,  figs.  10  and 
11.  1888. 

This  species  has  been  found  by  Humphrey  at  Amherst  and  this  is 
the  only  American  record.  His  description  follows  (’92,  p.  126.  See  also 
his  pi.  20,  figs.  103  and  104): 

“  Hyphae  of  medium  size,  short.  Zoosporangia  rare,  cylindric. 
Oogonial  branches  rarely  long,  straight  or  flexuous,  racemosely  arranged. 
Oogonia  terminal,  globular  or  elliptical,  densely  beset  with  rather  long, 
blunt  outgrowths  of  their  unpitted  walls,  the  apical  one  often  larger 
and  forming  an  evident  apiculus.  Antheridial  branches  and  antheridia 
wanting.  Oospores  from  one  to  four  in  an  oogonium,  globular  or  slightly 
flattened,  centric,  their  average  diameter  about  2910.. 

“  Massachusetts — Amherst.  Europe. 

“The  same  culture  which  yielded  A.  megasperma  for  the  first  time 
contained  a  small  amount,  all  I  have  seen,  of  this  form.  It  has  been 
referred  with  some  doubt  to  Archer’s  species,  since  it  fails  to  show  at 
all  a  feature  which  one  would  suppose,  from  that  author’s  account  and 
figures,  to  be  very  characteristic  of  his  plant;  namely,  the  development 
of  several  oogonia  in  a  series  from  a  single  hypha.  In  other  respects, 
however,  it  corresponds  too  closely  with  his  description  to  justify  one 
in  regarding  it  as  distinct.  Archer  saw  no  sporangia,  probably  not, 
as  he  thought,  because  he  found  it  too  late,  but  because  of  their  rarity. 
In  species  which  produce  sporangia  abundantly,  one  can  always  find 
empty  ones  on  plants  with  mature  oospores.  In  the  limited  material 
at  my  disposal,  I  have  been  able  to  find  but  a  single  one,  and  that  only 
long  after  it  was  emptied.  From  below  its  base  arose  a  branch  bearing 
an  oogonium.  This,  so  far  as  it  goes,  supports  Archer’s  conclusion  that 
the  plant  is  an  Achlya ,  which  seems  almost  certainly  correct.  The 
oogonial  branches  sometimes  show  the  incurving  mentioned  by  Archer, 
and  are  often  less  definitely  bent.  This  writer  states  that  an  oogonium 
may  contain  as  many  as  eight  or  ten  oospores;  but  I  have  never  seen 
more  than  four,  and  his  figures  show  no  more  than  three.  He  describes 
no  special  antheridial  branches,  but  says  that  the  antheridia  are  like 
those  of  A.  dioica  Pringsh.  As  these  latter  are  not  antheridia  at  all, 
one  would  expect  to  find,  as  is  the  case  with  American  specimens,  that 
the  species  has  no  true  male  organs.  As  will  be  seen  from  the  figures, 
the  spines  could  hardly  be  more  closely  set,  and  their  form  is  more  cylin¬ 
drical  than  conical. 

“This  and  the  next  species  [A.  stellata  deBary]  seem  to  be  closely 
related,  the  more  so  if  the  American  form  here  described  proves  to  be 
more  typical  than  Archer’s.” 


ACHLYA 


III 


The  species  is  very  near  A.  spinosa  deBary,  and  Fischer  considers 
it  as  the  same,  both  being  characterized  by  very  few  sporangia  (Archer 
found  none).  However,  as  that  species  has  antheridia  on  about  half  the 
oogonia  it  would  seem  unjustifiable  at  present  not  to  separate  them. 
Humphrey  regards  A.  cornuta  as  nearest  A.  stellata  deBary,  which  he 
says  is  almost  too  similar.  The  latter  has  no  antheridia,  thus  agreeing  with 
A.  cornuta  in  this  respect.  As  there  seem  to  be  no  differences  of  any 
consequence  between  the  last  two  species  we  are  treating  them  as  probably 
the  same. 

6.  Achlya  americana  Humphrey.  Trans.  Amer.  Phil.  Soc.  17:  116,  pi. 

14,  figs.  7,  9,  10;  pi.  15,  figs.  24,  25,  29;  pi.  16,  figs.  30-36;  pi.  18, 

figs.  69-73.  1892  [1893]. 

Plates  33  and  34 

Growth  not  dense,  consisting  of  stout  hyphae  with  more  slender 
ones  intermingled,  the  largest  up  to  1004  thick  at  base,  the  tips  pointed. 
Sporangia  long,  slender,  usually  more  or  less  fusiform  (one  of  about 
average  size  measured  22  x  3704) ;  emptying  normally,  the  spores  fur¬ 
nished  with  cilia  as  they  emerge  (Humphrey),  10.510.  thick.  Gemmae 
very  few,  not  peculiar,  elongated  and  formed  by  segmenting  hyphae, 
single  or  two  or  three  in  a  row.  Oogonia  numerous,  racemosely  borne 
from  the  base  to  the  tip  of  main  hyphae  on  short  stalks  which  are  usually 
straight  and  much  shorter  than  the  diameter  of  the  oogonia  (rarely 
oogonial  stalks  may  be  several  times  longer  than  diameter  of  oogonia) ; 
not  rarely  apical  on  main  threads  (fig.  2),  no  intercalary  ones  seen  (rarely 
intercalary,  Humphrey) ;  spherical,  rarely  distorted,  40-904,  most  about 
50-604  thick;  walls  hyaline,  rather  thin,  pits  numerous  and  obvious.  Eggs 
varying  little  in  size,  18.5-254,  the  great  majority  about  224  thick,  rarely 
a  very  small  one  about  half  size  occurs  with  the  normal  ones,  3-30  or  even 
more,  usually  6-12,  in  an  oogonium,  eccentric.  Antheridial  branches  an¬ 
drogynous,  occasionally  one  from  an  adjoining  strand,  one  or  two,  seldom 
more  on  each  oogonium;  arising  from  the  main  hyphae  near  the  oogonia 
or  rarely  from  the  oogonial  stalk.  Antheridia  elongated  and  closely 
applied  to  the  oogonia,  antheridial  tubes  developed  and  clearly  visible. 

Our  cultures  were  obtained  from  two  sources  in  vials  of  water  with 
a  little  trash  kindly  sent  us  in  June,  1920,  from  Woods  Hole,  Mass., 
by  Mr.  George  M.  Gray,  Curator  of  the  Marine  Biological  Laboratory. 
In  one  of  these  collections  there  were  a  good  many  oogonial  stalks  that 
were  as  long  as  or  even  longer  than  the  oogonial  diameter,  though  such 
were  greatly  in  the  minority;  in  the  other  strain  only  a  very  few,  per¬ 
haps  one  or  two  in  a  culture,  were  of  such  length.  It  is  strange  that 
the  species  has  never  appeared  in  any  of  our  North  Carolina  collections. 
Humphrey  reports  it  from  Massachusetts,  Pennsylvania,  Alabama,  and 
Louisiana,  and  he  speaks  of  it  as  “our  most  abundant  member  of  this 
genus,  and  indeed  of  this  family’’  so  far  as  he  has  observed.  The  only 


I  12 


THE  SAPROLEGNIACEAE 


foreign  records  of  this  species  we  have  met  with  are  by  Petersen  (’io,  p. 
524),  who  reduces  it  to  a  form  of  A.  polyandra  de  B.  and  calls  it  “forma 
Americana ,  ”  and  by  Minden  (’12,  p.  645)  who  reduces  it  to  a  variety  of 
*4.  deBaryana.  The  species  differs  easily  from  our  interpretation  of  A. 
deBaryana  in  the  short  androgynous  antheridial  branches,  short-stalked 
oogonia  and  smaller  eggs.  See  under  the  genus  and  under  A.  imperfecta 
for  comparisons  and  discussions. 

This  is  the  species  that  Humphrey  studied  with  sections  to  deter¬ 
mine  the  presence  or  absence  of  sexual  fusion,  and  he  came  to  the  con¬ 
clusion  that  no  fertilization  occurs  (’92,  p.  94).  This  conclusion  is, 
however,  in  all  probability  erroneous,  as  an  examination  of  his  own  fig¬ 
ures  will  show  (see  Trow  ’95,  p.  638;  and  ’99,  p.  163).  We  have  exam¬ 
ined  Humphrey’s  slides  (not  the  cytological  preparations)  generously 
lent  by  Dr.  D.  S.  Johnson,  and  find  his  plant  to  be  identical  with  ours 
from  Woods  Hole.  In  two  of  Humphrey’s  figures  (29a  and  29b)  ger¬ 
minating  eggs  are  shown. 

An  Irish  plant,  considered  a  variety  of  this  by  Trow,  has  not  been 
found  in  America  (see  p.  139).  It  is  probably  of  specific  rank. 


7.  Achlya  Orion  Coker  and  Couch.  Journ.  E.  Mitchell  Sci.  Soc.  36:  100. 


1920. 

Plates  34  and  35 

Hyphal  threads  long,  reaching  a  length  of  1.5  cm.  on  house-flies, 
more  slender  than  in  most  Achlyas,  from  10-404  thick  close  to  base, 
rarely  up  to  854  thick,  often  wavy;  usually  little  branched  and  pointed 
at  tips  when  young;  becoming  considerably  branched  with  age.  Spo¬ 
rangia  abundant,  cylindrical,  usually  borne  singly  on  the  tips  of  the  main 
hyphae  in  young  cultures,  renewed  by  cymose  branching,  often  forming 
several  clusters  at  regular  intervals  on  the  same  hypha,  irregular  and 
wavy  in  old  cultures,  12-37  x  36-6004  (rarely  up  to  9004).  Spores 
9-104  thick,  emerging  as  usual  in  Achlya ,  but  often  falling  to  the  bottom 
in  an  open  group  instead  of  forming  a  sphere  at  the  sporangium  mouth. 
Oogonia  abundant  on  flies,  grubs,  and  vegetable  media,  spread  over  the 
entire  culture  from  the  bases  of  hyphae  to  tips,  giving  the  culture  a  lacy 
interwoven  or  net-work  appearance;  the  diameter  30-604,  commonly 
32-48;x;  usually  borne  singly  on  long,  crooked,  recurved  stalks  which 
arise  racemosely  from  main  hyphae  and  which  vary  in  length  from  2-10 
times  the  diameter  of  the  oogonia;  often  oogonial  stalks  may  branch 
bearing  two  oogonia,  and  rarely  oogonia  may  be  borne  on  a  stalk  which 
arises  directly  from  another  oogonial  wall;  \  ery  rarely  intercalary;  oogo¬ 
nial  wall  usually  without  pits  (except  where  the  antheridial  tubes  enter) 
when  grown  on  flies  or  grubs,  but  as  a  rule  with  pits  when  grown  on 
boiled  corn.  Eggs  1-8,  usually  1  or  2  in  each  oogonium;  25-454  in 
diameter,  most  33-364,  eccentric  when  ripe,  with  one  large  oil  drop; 
usually  spherical,  but  often  elliptical  from  pressure.  Antheridial  branches 


PLATE  33 


PLATE  33 


ACHLYA  AMERICANA 

Fig.  I.  Habit  of  plant.  X  68. 

Fig.  2.  Apical  oogonium  (only  one  of  its  kind  seen).  X  278. 

Fig.  3.  Typical  sporangia.  X  188. 

Fig.  4.  Typical  oogonium  and  antheridia.  X  503- 

Fig.  5.  Oogonium  with  diclinous  antheridium  and  an  unusually  long  oogonial  stalk.  X  278. 
Fig.  6.  Irregularly-shaped  oogonium.  X  278. 

Fig.  7.  Two  typical  oogonia,  one  with  a  slight  protuberance.  X  278. 

Fig.  8.  Oogonium  with  a  crooked  and  irregular  stalk,  also  with  a  slight  protuberance  as  in 
fig.  7.  X  278. 


PLATE  33 


ACHLYA  AMERICANA. 


PLATE  34 


ACHLYA  AMERICANA  [ABOVE],  x  6. 
ACHLYA  ORION  [BELOW].  X  4- 


PLATE  35 


PLATE  35 
Achlya  Orion 

Figs.  I  and  2.  Oogonia  with  single  egg  and  unbranched  antheridia.  X  233. 

Fig.  3.  Oogonium  with  branched  antheridia.  X  233. 

Fig.  4.  Oogonial  stalk  arising  from  the  wall  of  another  oogonium.  X  233- 

Fig.  5.  Eggs  showing  a  late  stage  in  maturation  with  several  oil  droplets  not  yet  united 
into  one  large  drop.  X  387. 

Fig.  6.  Oogonium  with  a  typical  long  stalk.  X  233. 

Fig.  7.  Cluster  of  oogonia,  one  of  which  is  barrel-shaped  with  the  eggs  in  distal  end  and  a 
perforated  wall  partly  separating  the  two  ends.  Grown  on  a  bit  of  boiled  corn 
grain  in  distilled  water  at  room  temperature.  X  233. 

Fig.  8.  Oogonia  on  a  very  much  distorted  oogonial  stalk,  as  typical  when  cultivated  three 
days  in  electric  oven  with  temperature  of  36°  centigrade.  X  233. 

Fig.  9.  Oogonium  with  diclinous  antheridium  and  ripe  egg,  showing  oil  drop.  X  387. 

Fig.  10.  Oogonium  with  antheridia  arising  from  oogonial  stalk  and  main  hyphae  also.  X 
233- 

Fig.  11.  Habit  sketches  to  show  appearance  of  oogonia  and  antheridia  and  occasional 
behavior  of  spores.  X  97. 

Figs.  12  and  13.  Habit  of  sporangia.  X  97. 

Fig.  14.  Spores  emerging  from  cysts.  X  720. 

Fig.  15.  Habit  of  sporangia.  X  97- 


PLATE  35 


ACHLYA  ORIOX. 


ACHLYA 


1 13 

almost  always  androgynous,  usually  arising  from  the  oogonial  stalk  it¬ 
self,  less  often  from  the  main  hypha;  rarely  diclinous;  antheridia  on 
about  75%  of  the  oogonia,  one  or  two  on  an  oogonium,  tuberous;  an- 
theridial  tubes  obvious,  penetrating  the  oogonia  and  reaching  the  eggs. 

The  species  seems  to  be  quite  rare,  having  been  recognized  only 
twice  in  considerably  over  two  thousand  collections  made  by  us.  It  was 
found  in  some  water  and  trash  collected  from  the  west  branch  above 
the  Meeting  of  the  Waters  (No.  6  of  September  26,  1919),  and  in  the 
same  kind  of  material  from  the  branch  in  Battle’s  Park  behind  Dr. 
Pratt’s  residence  (No.  4  of  June  10,  1920).  The  description  has  been 
made  from  cultures  descended  from  a  single  spore. 

Our  plant  can  be  distinguished  (with  the  unaided  eye)  from  most 
other  Chapel  Hill  Achlyas  by  the  network  appearance  given  it  by  the 
oogonia,  which  are  evenly  scattered  over  the  entire  culture  from  the 
bases  of  the  hyphae  to  the  tips.  Achlya  racemosa  approaches  this  net¬ 
work  appearance  more  than  any  other  species  of  Achlya,  but  in  it  the 
oogonia  are  not  nearly  so  abundant  nor  do  they  extend  entirely  to  the 
tips  of  the  hyphae.  In  some  species,  such  as  Achlya  oblongata  or  Achlya 
conspicua ,  the  oogonia  are  borne  in  a  definite  zone  near  the  substratum 
and  from  half  to  two-thirds  of  the  length  of  the  hyphae  from  the  tips 
backwards  are  without  oogonia.  In  the  Prolijera  group  the  oogonia 
are  scattered  more  or  less  over  the  entire  culture,  but  the  big  hyphae 
and  long  sporangia  dissipate  the  network  appearance. 

If  we  ignore  the  egg  structure,  the  present  species  seems  to  be  closest 
to  Achlya  polyandra  Hildb.  The  two  plants  resemble  each  other  in  the 
long,  racemose  oogonial  branches  which  are  recurved  at  the  tip;  in  the 
often  branched  antheridial  stalks  which  arise  chiefly  from  the  oogonial 
branches;  and  in  the  smooth  oogonial  walls  which  are  normally  without 
pits  except  where  the  antheridia  touch.*  The  two  species  are  readily 
distinguished,  however,  by  the  difference  in  the  number  of  eggs  in  the 
oogonia,  and  in  the  size  and  structure  of  the  eggs.  In  Achlya  polyandra 
the  number  of  eggs  varies  from  five  to  twenty-five,  the  usual  number 
being  ten  to  fifteen,  while  in  A.  Orion  the  number  varies  from  one  to 
eight,  the  usual  number  being  one  or  two.  In  Achlya  polyandra  the  eggs 
are  said  to  be  centric  with  an  average  diameter  of  27^,  but  in  our  plant 
they  are  eccentric  and  most  with  a  diameter  of  between  33  and  36;x. 
There  are,  moreover,  other  differences  which  are  more  subject  to  variation. 
In  Achlya  polyandra  the  sporangia  are  reported  as  often  not  abundant, 
and  secondary  ones  rare;  while  in  our  plant  both  primary  and  secondary 

*Though  pits  are  rarely  seen  when  the  plant  is  cultivated  on  flies  or  grubs  they  are  not 
at  all  unusual  in  cultures  on  a  piece  of  boiled  corn  grain.  Compare  A.  flagellata  for  similar 
variations. 


THE  SAPROLEGNIACEAE 


1 14 

sporangia  are  abundant.  The  species  is  named  for  the  nebula  in  Orion,  which 
a  photograph  of  the  magnified  culture  somewhat  resembles  (see  pi.  34). 

The  following  series  of  experiments  were  made  to  test  the  effects 
of  different  temperatures  on  growth  and  reproduction.  All  cultures 
were  made  from  strains  descended  from  a  single  spore  (from  No.  6  of 
September  26,  1919).  Inoculations  were  uniformly  made  by  cutting 
out  near  the  periphery  of  the  mycelium  small  squares  of  corn  meal  agar, 
on  which  the  fungus  was  actively  growing,  and  placing  on  these  squares 
termite  ants,  flies,  or  vegetable  media,  etc.,  for  food.  Distilled  water 
was  used  unless  otherwise  stated. 

Culture  on  fly,  healthy,  and  just  beginning  to  form  sporangia  and  oogonia  was  put  in 
electric  incubator,  temperature  40°  C.  Examined  twenty-three  hours  later  and  found 
to  be  dead.  Repeated  with  same  result. 

Check  culture  on  fly  left  in  room,  temperature  21.50  C.  Formed  many  normal  asexual 
and  sexual  reproductive  organs.  Repeated  with  same  result. 

Culture  on  mushroom  grub  in  sterilized  spring  water  was  put  in  incubator  at  tempera¬ 
ture  of  36°  C.  Examined  two  days  later:  mycelium  thick,  long  (1  cm.  from  host), 
mostly  straight  but  some  slightly  wavy  hyphae.  Threads  unusually  densely  filled 
with  protoplasm.  No  sporangia.  A  good  many  oogonial  initials.  No  harmful  effects 
of  bacteria  observed.  Reexamined  twenty-eight  hours  later:  mycelium  still  growing 
vigorously.  No  sporangia  formed.  Many  oogonia  formed,  a  majority  of  which  had 
queer  stalks  which  wer  every  long  and  coiled  like  a  cork-screw  (see  pi.  35,  fig.  8).  In 
most  cases  at  tips  of  these  stalks  abortive  attempts  to  form  oogonia  were  made, 
resulting,  as  a  rule,  in  from  one  to  three  swellings. 

Two  check  cultures  under  same  conditions  as  above,  except  in  room  temperature  of  20° 
C.  Growth  normal,  many  sporangia  and  oogonia  formed  during  the  third  day. 
Culture  on  piece  of  boiled  corn  grain  embryo  was  put  in  incubator  at  temperature  of 
36°  C.  A  few  sporangia  produced,  some  of  which  emptied  normally,  others  did  not 
empty,  though  spores  were  formed.  As  compared  with  cultures  in  room  temperature 
a  very  small  number  of  oogonia  were  produced,  and  about  1  out  of  10  of  these  formed 
eggs  which  had  the  appearance  of  being  normal.  About  a  third  of  the  oogonia  had  the 
curiously  coiled  stalks  as  cultures  on  grub  at  same  temperature  (above).  Antheridia 
usually  of  normal  shape  on  normal  oogonia,  but  on  oogonia  with  coiled  stalks  anther¬ 
idia  also  coiled.  Repeated  with  essentially  the  same  results. 

Culture  on  piece  of  boiled  corn  grain  endosperm  (horny  and  starchy)  was  put  in  incubator 
at  temperature  of  36°  C.  Sporangia  produced  in  abundancp,  many  emptying  normally; 
others  forming  spores  which  encysted  within  the  sporangium.  Compared  with 
cultures  in  room  temperature  a  considerably  larger  number  of  normal  oogonia  with 
good  eggs  were  formed,  and  compared  with  culture  in  incubator  on  termites  a 
smaller  number  of  oogonia  with  coiled  stalks  were  formed.  This  culture  approached 
far  nearer  in  appearance  the  normal  room  cultures  than  any  yet  cultivated  in  oven. 
Repeated  with  same  results.  In  one  of  these  cultures  two  little  bits  of  the  starchy 
part  of  grain,  size  of  pin  head,  broke  oft'  and  were  inoculated  by  spores.  Both  formed 
tiny  cultures  about  3  mm.  across.  The  hyphae  were  very  delicate,  about  one-third  the 
normal  diamater.  The  sporangia,  produced  in  plenty,  were  mostly  relatively  as  small. 
The  spores,  however,  were  normal  size,  9-iOju  in  diameter.  A  good  many  oogonia 
produced  of  normal  size  (50-80^),  with  eggs  equally  normal  (average  33m)- 


ACHLYA 


1 15 

Four  cultures  on  termite  ants  put  in  incubator  at  temperature  of  36°  C.  produced  many 
oogonia  and  antheridia  with  coiled  stalks;  very  few  good  eggs. 

On  nutrient  agar  in  one  per  cent  solution  of  levulose  (room  temperature).  Hyphae 
normal.  A  good  many  sporangia  formed  which  emptied  normally.  Very  few  oogo¬ 
nia  and  these  smaller  than  usual  and  abortively  shaped.  Culture  washed  and  trans¬ 
ferred  to  pure  water.  A  great  many  perfectly  normal  oogonia  formed  with  normal 
eggs. 

On  nutrient  agar  in  ten  per  cent  solution  of  levulose  (room  temperature).  Hyphae  normal. 
A  large  number  of  sporangia  formed,  all  of  which  emptied.  Spores  sprouted  immed¬ 
iately  without  coming  out  of  cysts.  Many  oogonia  and  about  one-third  of  these  with 
eggs;  the  average  number  of  eggs  3-4,  a  few  oogonia  with  8. 


8.  Achlya  proliferoides  n.  sp. 

Plate  36 

Growth  moderately  dense  and  strong,  reaching  a  length  of  about 
I  cm.  on  a  mushroom  grub.  Hyphae  moderately  branched,  variable 
in  size,  usually  wavy  and  irregular,  the  tips  hyaline  and  dying  back 
here  and  there  as  in  A.  imperfecta  and  A.  flagellata.  Sporangia  sub- 
cylindrical,  usually  bent,  often  with  several  openings;  about  35-45^ 
thick  as  a  rule,  short  or  long,  at  times  up  to  1425(0.  long.  Spores  1 1 — 1 2 r jl 
thick,  double  ones  not  rare,  often  falling  to  the  bottom  in  an  open  group 
on  emerging.  Oogonia  abundant,  spherical,  smooth,  40-55(0.  in  diam¬ 
eter,  racemosely  borne  on  stalks  that  are  about  1-1  %  times  as  long 
as  the  diameter  of  the  oogonia;  wall  hyaline,  not  thick;  pits  numerous 
(usually),  but  not  very  conspicuous.  Eggs  eccentric,  with  a  large  oil 
drop,  about  18-24(0.  in  diameter,  often  elliptic,  the  great  majority  always 
going  to  pieces  before  maturity  on  ordinary  media.  Antheridial  branches 
numerous,  diclinous  (mostly)  or  androgynous,  usually  long,  contorted 
and  much-branched,  in  many  cases  coiling  themselves  about  certain 
selected  hyphae  which  may  or  may  not  bear  oogonia.  Antheridia,  one 
or  several,  on  every  oogonium,  elongated,  applying  their  sides  to  the 
oogonium  or  touching  it  by  several  blunt,  foot-like  processes. 

Not  nearly  so  common  in  Chapel  Hill  as  A.  imperfecta  or  as  A. 
flagellata ,  but  not  rarely  found  with  them,  as  in  branch  below  Cobb’s 
Terrace  (No.  3  of  July  24,  1918.  Type). 

As  a  rule  very  few  and  often  none  of  the  eggs  mature  in  normal 
cultures,  such  as  on  insects  or  corn  grain  in  distilled  water.  They  fall 
to  pieces  into  scattered  granules  or  amorphous  masses  as  soon  as,  or 
before,  a  thin  wall  is  formed.  The  oogonia  often  halt  in  their  develop¬ 
ment  and  send  out  a  branch  which  bears  another  oogonium  just  as  in 
A.  imperfecta.  At  times,  however,  instead  of  forming  another  oogon¬ 
ium  this  branch  may  develop  into  an  antheridial  branch  (fig.  3).  Like 
A.  imperfecta  again,  the  stalk  of  the  oogonium  may  not  rarely  carry  a 
branch  near  its  base  which  usually  bears  an  oogonium.  The  tendency 
to  coiling  in  A.  proliferoides  is  shown  not  only  by  the  antheridial  branches 
wrapping  themselves  about  the  hyphae,  but  also  by  the  frequent  coiling 


THE  SAPROLEGNIACEAE 


1 16 

of  the  oogonial  stalk  towards  the  end  (fig.  6),  and  by  the  hyphae  not 
rarely  coiling  themselves  into  a  flat  spiral  like  a  watch  spring. 

The  antheridia  while  usually  in  the  great  majority  diclinous  are  not 
consistently  so  and  are  very  variable  in  this  respect.  On  mushroom 
grubs  or  bits  of  boiled  corn  grain  very  few  androgynous  antheridia  may 
appear  or  they  may  be  numerous,  these  changes  appearing  in  consecu¬ 
tive  cultures  of  the  same  pure  strain. 

9.  Achlya  flagellata  n.  sp. 

Plate  37 

Growth  stout  and  moderately  dense,  reaching  a  length  of  about 
1  cm.  on  a  mushroom  grub  or  ant  larva.  Hyphae  branching,  tapering 
outward,  up  to  150^  thick  near  the  base,  more  or  less  crowded  and  un¬ 
even,  the  tips  hyaline  and  often  dying  and  renewed  from  one  side  below 
as  in  all  members  of  this  group.  Sporangia  plentiful,  subcylindrical, 
very  variable  in  size,  often  bent  and  at  times  with  more  than  one  open¬ 
ing,  scattered  or  clustered.  Spores  often  falling  to  the  bottom  in  an 
open  cluster  on  emerging,  about  11-11.5:0.  thick.  Gemmae  abundant, 
usually  in  rows  from  the  segmentation  of  the  distal  parts  of  hyphae, 
short  or  long,  usually  more  or  less  cylindrical,  but  often  pear-shaped  or 
ten-pin-shaped  or  at  times  very  irregular;  usually  becoming  sporangia 
on  change  of  medium  and  discharging  through  an  elongated  papilla  at 
either  end.  Oogonia  abundant,  typically  spherical,  but  not  rarely  ir¬ 
regular  by  abnormal  growth  on  one  side,  and  one  or  two  papillate  projec¬ 
tions  may  be  seen  rarely;  usually  about  48-75^  thick,  rarely  up  to  ioo;j., 
racemosely  borne  on  short,  slender  stalks  about  as  long  usually  as  the 
diameter  of  the  oogonia  or  a  little  shorter,  rarely  on  longer  stalks  and 
quite  rarely  intercalary;  wall  hyaline,  not  thick  (about  1.5^);  pits  very 
variable,  perhaps  more  often  absent,  but  again  numerous  and  rather 
easily  seen,  about  5.5:0.  wide.  Eggs  spherical,  eccentric  with  a  large  oil 
drop,  1— 10  (rarely  20)  in  an  oogonium,  mostly  2-6,  diameter  26-35:0., 
most  about  28^.,  rarely  small  ones  down  to  i8;o.  may  be  mixed  with  the 
others.  Antheridial  branches  abundant,  usually  much  branched  and 
irregular,  often  so  much  so  as  to  make  an  intricate  network  like  a  group 
of  rhizoids,  originating  laterally  and  apically  from  hyphae  which  may  or 
may  not  bear  oogonia  and  applying  themselves  to  oogonia  on  the  same 
or  on  other  threads  or  to  both;  more  often  diclinous  than  androgynous, 
perhaps  about  three  times  as  often  usually,  but  varying  in  this  respect; 
the  antheridial  branches  never  arising  from  the  stalks  of  the  oogonia. 
Antheridia  on  nearly  all  oogonia,  one  or  several,  elongated  with  the  side 
on  the  oogonium,  frequently  touching  the  oogonium  with  foot-like  pro¬ 
jections;  antheridial  tubes  easily  observed. 

Very  common  in  Chapel  Hill  in  springs,  brooks,  ditches  and  creeks, 
as  in  spring  near  Clark’s  schoolhouse  (No.  1  of  July  25,  1918),  in  Arbore¬ 
tum  spring,  in  Battle’s  branch,  etc.  Also  found  in  some  material  sent  from 
Chimney  Rock,  N.  C.,  June  10,  1920  (Miss  Hoffmann,  coll.),  differing  from 


PLATE  36 


PLATE  36 

Achlya  proliferoides 

Fig.  I.  Hypha  with  antheridial  branches  entwined  around  it.  X  167. 

Fig.  2.  Oogonium  with  ripe  eggs.  X  447. 

Fig.  3.  Habit  of  oogonia  and  antheridia.  X  167. 

Fig.  4.  Spores  sprouting  in  sporangium  and  below  on  same  hypha  two  gemmae.  X  167. 
Fig.  5.  Oogonium  growing  from  an  abortive  one.  X  247. 

Fig.  6.  Spiral-shaped  oogonial  stalk  (culture  on  corn  grain).  X  167. 

Fig.  7.  Oogonium.  X  247. 

Fig.  8.  Contorted  antheridial  branches.  X  167. 

Fig.  9.  Gemmae.  X  108. 

Fig.  10.  Hyphae  showing  pointed  tip  and  atrophied  tips  renewed  from  below.  X  108. 


PLATE  36 


ACHLYA  PROLIFEROIDES, 


PLATE  37 


PLATE  37 
Achlya  flagellata 

Fig.  I.  Habit,  showing  androgynous  antheridia.  X  41. 

Fig.  2.  Angular  oogonium.  X  447. 

Fig.  3.  Antheridial  branches  on  tip  of  hypha  curling  back  to  oogonia.  X  167. 

Pig.  4.  Laterally  elongated  oogonium  with  blunt  papilla  and  ingrowth  from  below.  X 
250. 

Fig.  5.  Oogonia  with  diclinous  antheridia.  X  167. 

Fig.  6.  Empty  sporangia,  sporangium  with  sprouting  spores,  gemmae,  and  abortive  oogo¬ 
nium.  X  108. 

Fig.  7.  Gnarled  gemmae.  X  60. 

Fig.  8.  Laterally  elongated  oogonium  with  an  ingrowth  from  below.  X  250. 

Fig.  9.  Habit,  showing  diclinous  antheridia.  X  60. 

Fig.  10.  Part  of  a  dictiosporangium.  X  720. 

Fig.  II.  Oogonium  with  ripe  eggs.  X  447. 

Fig.  12.  Sporangium  emptied  in  corn  meal  agar.  X  41. 


PLATE  37 


ACHLYA  FLAGELLATA 


ACHLYA 


ii  7 


the  Chapel  Hill  plants  in  no  way  except  for  the  short  stalked  oogonia, 
more  numerous  eggs,  and  more  branched  antheridial  branches.  Again 
found  in  some  material  collected  at  Fayetteville,  N.  C.,  July  io,  1920 
(M  iss  Holland,  coll.).  Distinguished  from  all  other  members  of  its  group 
except  A.  a  planes  by  the  decidedly  larger  eggs,  and  even  in  the  latter 
species  the  eggs  do  not  average  so  large  and  the  antheridia  are  always 
diclinous.  Ward ’s  figures  1-14,  plate  22  (1883),  while  labelled  A .  polyandra 
deB.,  look  more  like  the  present  species. 

This  is  the  plant  treated  by  us  as  A.  deBaryana  in  Mycologia  4: 
319,  pi.  78,  1912,  but  we  now  think  it  cannot  be  that  species.  The  un¬ 
pitted  walls  of  the  oogonia  together  with  the  always  (practically)  androg¬ 
ynous  antheridia  that  arise  near  the  oogonia  of  the  latter  must  exclude 
our  plant. 

The  antheridial  branches  of  A .  flagettata  are  unlike  all  others  we  have 
seen:  only  A.  proliferoides  may  have  them  so  intricately  branched  and 
such  branching  is  not  so  common  even  in  that  species;  neither  are  they 
so  complex  in  A.  imperfecta  (No.  1  of  July  20,  1918),  though  often  long 
and  complex  in  that  species;  furthermore  the  short  and  simple  androg¬ 
ynous  branches  of  A.  americana  and  at  times  of  A.  imperfecta  are  not 
present  in  A.  flagellata;  and  the  antheridial  branches  often  arise  from 
the  stalks  of  the  oogonia  in  A.  imperfecta  and  never  in  this.  The  oogonia 
are  much  inclined  to  proliferate  and  empty  their  contents  into  a  new 
one  by  an  outgrowth,  as  is  true  in  all  members  of  the  group,  and  in  this 
species  this  often  leads  to  sac-like  shapes,  with  or  without  a  constriction 
(pi.  37,  fig.  11)  or  to  other  unusual  forms  (as  said  above  a  few  papillate 
projections  are  to  be  seen  rarely).  Oogonial  initials  may  halt  after  reach¬ 
ing  full  size  and  become  gemmae,  or  their  stalks  may  become  part  of 
a  gemma  when  the  main  hyphae  are  segmented.  It  is  also  quite  easy 
to  find  oogonial  stalks  that  are  branched  at  right  angles  below  with  a 
secondary  oogonium  on  the  branch,  as  in  A.  caroliniana,  and  all  the  other 
members  of  this  group  that  we  have  seen. 

In  regard  to  the  pits  we  have  here  the  usual  uncertainty  of  the  group. 
Without  apparent  cause  a  group  of  oogonia  here  and  there  may  show 
them  plainly,  either  one  or  many,  while  the  great  majority  in  the  same 
culture,  as,  e.g.,  on  a  corn  grain  or  a  mushroom  grub,  may  have  none 
except  for  the  easily  seen  thin  places  under  the  antheridia.  The  pits 
are  never  so  large  and  conspicuous  as  in  A.  conspicua  or  in  the  Ferax 
group  of  Saprolegnia.  When  grown  on  nutrient  agar  the  sporangia 
may  open  and  discharge  their  spores  inside  the  agar.  In  such  case  the 
spores  do  not  make  a  sphere  at  the  tip,  but  flow  back  and  form  a  layer 
around  it  (fig.  12).  The  species  is  subject,  though  rarely,  to  the  attacks 
of  an  Olpidiopsis. 


1 1 8 


THE  SAPROLEGNIACEAE 


It  is  also  to  be  noted  that  while  the  gemmae  in  this  species  may 
become  somewhat  loosened  at  the  points  so  as  to  bend  back  a  little, 
they  are  far  less  inclined  to  this  than  in  A.  imperfecta,  and  we  have  never 
seen  them  fall  away  as  so  often  happens  in  that  plant.  Dictiosporangia 
are  not  rarely  observed  and  have  been  illustrated  by  us  (’12,  pi.  78). 


10.  Achlya  imperfecta  n.  sp. 

Achlya  deBaryana  var.  intermedia  Minden.  Krypt.  FI.  Mark  B.  5: 
545-  1912. 

Plates  38  and  39 

Growth  dense  or  rather  open,  not  very  long,  many  stout  hyphae 
with  more  slender  branches,  tips  hyaline,  often  dying  and  then  a  new 
growing  point  produced  below.  Sporangia  plentiful,  subcylindrical,  little 
larger  than  the  hyphae  that  bear  them,  not  very  long  as  a  rule,  often 
irregular  and  twisted.  Spores  about  10-11.59.  thick,  dark,  emerging  as 
usual  but  often  falling  to  the  bottom  in  an  open  group  instead  of  form¬ 
ing  a  sphere  at  the  sporangium  mouth.  Gemmae  formed  by  the  seg¬ 
mentation  of  the  hyphae,  therefore  mostly  subcylindrical  and  in  rows, 
blit  often  ovate  and  frequently  with  knobs  or  projections  at  one  or  both 
ends.  Any  part  of  the  culture  may  be  segmented  into  gemmae  even 
to  parts  of  the  antheridial  branches.  They  often  become  loosened  from 
each  other  in  part,  rather  rarely  completely  separating  and  falling  singly 
to  the  bottom.  Oogonia  usually  abundant,  spherical,  37-6010.  thick, 
most  about  40-4510.,  borne  racemosely  on  short  stalks  about  times 

as  long  as  the  diameter  of  the  oogonia;  wall  without  pits,  or  with  several 
to  numerous  small,  inconspicuous  ones;  from  the  basal  wall  a  protuber¬ 
ance  of  varying  length  is  present  in  many  cases,  and  there  are  rarely 
present  one  or  two  papillate  protuberances  (pi.  38,  figs.  2  and  8).  Eggs 
eccentric,  with  a  large  oil  drop,  2-8  in  an  oogonium,  commonly  4-6, 
diameter  17-239.,  most  about  19.5-209.,  often  elliptic  from  pressure. 
The  great  majority  of  the  eggs  go  to  pieces  before  maturity.  Anther¬ 
idial  branches  androgynous  or  declinous,  variable  in  origin  and  length, 
usually  branched  and  irregular,  arising  from  hyphae  that  also  bear  oogon¬ 
ia  and  then  applying  themselves  to  nearby  oogonia  or  most  often  by 
extensive  growth  and  branching  to  more  distant  oogonia  either  on  the 
same  or  other  hyphae;  or  certain  threads  may  give  rise  to  antheridial 
branches  only  which  then  seek  out  oogonia  on  other  threads. 


Found  many  times  in  Chapel  Hill  in  springs,  ditches,  branches  and 
creeks.  Also  found  in  material  collected  near  Fayetteville,  N.  C.,  July  10, 
1920,  by  Miss  Holland.  Pieters  illustrates  (unpublished  notes)  a  species 
that  is  certainly  this  or  A .  proliferoides,  the  antheridia  sometimes  androgy¬ 
nous,  prevailingly  diclinous.  As  he  shows  no  coiling  antheridial  branches 
we  refer  his  plant  provisionally  to  this  species.  The  plant  he  illustrates  is 
presumably  the  one  he  has  studied  in  various  media  under  the  name  A. 
prolifera  (’15b,  p.  529)  as  his  drawings  are  labelled  A.  prolifera.  The  plant 


PLATE  38 


PLATE  38 
Achlya  imperfecta 

Fig.  i.  Habit  of  plant  showing  both  diclinous  and  androgynous  antheridia.  X  188. 
Fig.  2.  Angular  and  papillate  oogonium  with  an  abnormally  large  egg.  X  503. 

Fig.  3.  Oogonia  and  antheridia.  X  188. 

Fig.  4.  Habit.  X  47- 

Fig.  5.  Oogonium  with  mature  eggs.  X  503. 

Fig.  6.  Oogonia  and  antheridia.  X  188. 

Fig.  7.  Oogonia  and  antheridia.  X  278. 

Fig.  8.  Oogonium  with  blunt  apical  papilla.  X  503. 


PLATE  3S 


ACHLYA  IMPERFECTA 


- 

\ 


'teff 


1  •: 


PLATE  39 


PLATE  39 
Achlya  imperfecta 


Fig.  i.  Empty  sporangia  with  gemmae.  X  113. 

Fig.  2.  Spores  of  various  sizes.  X  503. 

Fig.  3.  Spore  with  cilia.  X  503. 

Fig.  4.  Spore  mass  which  emerged  from  sporangium  without  breaking  up  into  spores. 

(In  maltose  and  peptone  solution.)  X  278. 

Fig.  5.  Oogonium  in  empty  sporangium,  only  case  observed.  X  278. 

Fig.  6.  Various  forms  of  hyphal  tips.  X  188. 

Fig.  7.  Oogonium  with  very  small,  abnormal  eggs.  In  this  culture  the  eggs  often  went  to 
pieces.  X  278. 

Fig.  8.  Part  of  a  dictiosporangium.  X  503- 

Fig.  9.  Oogonium  in  which  eggs  went  to  pieces.  Sporangia  beneath.  X  278. 

Fig.  10.  Oogonia  and  antheridia  of  the  A.  americana  type.  X  47. 


PLATE  39 


ACHLVA  IMPERFECTA 


ACHLYA 


119 

studied  by  Ward  (’83)  and  illustrated  by  him  as  A.  polyandra  deB.  may  be 
this,  but  looks  more  like  A .  ft agellata.  Horn ’s  plant,  treated  as  A .  polyandra 
deB.  (’04),  may  also  be  the  present  species  (see  note  under  the  genus). 

All  of  the  variations  in  the  antheridial  branches  mentioned  above 
are  to  be  found  in  the  same  culture,  as  e.g.,  on  a  mushroom  grub  or  bit 
of  boiled  corn  grain.  All  the  oogonia  of  a  series  along  a  certain  thread  may 
have  diclinous  antheridia  (pi.  38,  fig.  4),  another  series  may  have  only 
short  androgynous  ones  (pi.  39,  fig.  10),  another  may  have  long  androgynous 
ones,  and  another  have  both  androgynous  or  diclinous  ones  indiscriminately. 
An  androgynous  origin  is  perhaps  the  more  common.  Not  at  all  rarely 
the  antheridial  branches  arise  from  the  stalks  of  the  oogonia,  thus  differing 
from  A.  fl  agellata. 

In  the  behavior  of  the  contents  of  the  sporangia  many  variations 
occur.  Masses  of  undivided  protoplasm  of  all  sizes  may  be  ejected 
with  the  spores  and  at  times  the  entire  mass,  undivided,  escapes  as  a 
whole  (pi.  39,  fig.  4).  See  p.  9  for  references  to  similar  cases. 

It  was  in  this  species  that  we  observed  the  only  two  cases  of  pro¬ 
liferation  through  empty  sporangia  that  we  have  found  in  Achlya.  In 
one  case  the  hypha  simply  extended  itself  through  the  sporangium; 
in  the  other  there  was  formed  a  stalked  oogonium  in  the  sporangium, 
the  hypha  extending  on  through  beyond.  We  know  of  no  reference  in 
the  literature  to  internal  proliferation  of  any  kind  in  Achlya  except  by 
Petersen,  who  says  that  he  has  seen  “zoosporangia  which  had  prolifer¬ 
ated  in  undoubted  species  of  Achlya"  (’10,  p.  520). 

For  a  discussion  of  the  relationships  of  this  species  to  A.  proliferoides, 
which  is  very  near,  and  to  other  members  of  the  group,  see  discussion 
under  the  genus.  Achlya  americana  is  also  near,  but  it  is  certainly  not 
the  same.  The  antheridial  branches  are  all  short  and  intermingled 
with  the  oogonia  in  origin,  the  eggs  are  more  numerous  (4-20,  usually 
6-12),  and  the  oogonia  average  a  little  larger  (40-90^,  most  about  50- 
60[a).  The  eggs,  also,  are  a  little  larger  (18. 5-25^,  most  about  22\x). 

Among  such  a  confusion  of  forms,  or  descriptions  of  forms,  it  is  a 
pleasant  relief  to  find  one  described  that  is  apparently  just  like  ours. 
This  is  Minden’s  A.  deBaryana  var.  intermedia ,  which  seems  identical 
except  that  he  does  not  mention  the  early  dissolution  of  most  of  the 
eggs.  He  describes  his  plants  as  follows: 

“In  structure  of  mycelium  and  length  of  the  oogonial  stalk  re¬ 
sembling  the  typical  form.  Differs  in  the  antheridial  branches  arising 
often  from  the  oogonial  stalks  as  well  as  from  the  main  branches  and  in 
their  being  longer  and  more  bunched,  and  running  farther,  thus  often 
attaching  themselves  to  more  distant  oogonia,  and  then  often  diclinous. 
Pits  not  always  obvious,  and  at  times  entirely  absent.  Moreover, 


120 


THE  SAPROLEGNIACEAE 


many  hyphae  occur  which  bear  only  antheridial  branches.  Were  the 
diclinism  preponderant  this  would  approach  A.  prolifera;  other  char¬ 
acters  are  like  A.  polyandra.  This  then  occupies  an  intermediate  posi¬ 
tion.”  Found  in  the  Luneburg  Heath,  near  Hamburg.  Germany. 

The  species  name  we  give  the  Chapel  Hill  plant  refers  to  the  failure 
of  most  of  the  eggs  to  reach  maturity.  The  name  Achlya  intermedia  has 
been  used  by  Bail  and  is  not  available  (see  under  Saprolegnia  monoica). 

ii.  Achlya  Klebsiana  Pieters.  Bot.  Gaz.  60:  486,  pi.  21,  figs.  1-4.  1915. 

Plate  40 

Threads  moderately  short  to  long,  growth  on  termites  varying  from 
4-14  mm.  across;  moderately  stout,  about  50-944  thick  at  the  base  and 
narrowing  gradually  to  the  bluntly  pointed  tips;  branches  not  very 
numerous,  the  radiating  main  threads  obvious  to  the  naked  eye.  Pri¬ 
mary  sporangia  plentiful,  mostly  from  40-54  x  432-8774,  although  some 
on  very  small  hyphae  are  as  small  as  20  x  1354;  secondary  sporangia 
abundant,  usually  including  also  a  part  of  the  hypha  below  the  primary 
sporangium;  at  times  many  very  small  sporangia  arising  on  slender 
hyphae  form  large  gemmae.  Sporangia  emptying  as  normally  in  Achlya, 
but  showing  all  the  usual  variations  and  also  a  unique  one  (see  below) ; 
spores  about  11-134  thick,  forming  a  rather  loose  hollow  sphere  about 
the  mouth;  usually  some  of  the  spores  do  not  escape,  but  encyst  within 
the  sporangium.  Gemmae  formed  abundantly  by  the  segmentation  of 
the  old  hyphae  into  dense,  more  or  less  irregular  rods,  and  by  the  incom¬ 
plete  development  of  sporangia-like  tips;  after  a  rest  becoming  sporangia 
and  emptying  by  a  papilla  of  very  variable  length  or  sprouting  by  many 
threads  or  less  often  forming  many  very  small  sporangia  on  the  ends 
of  the  sprouting  threads.  Oogonia  plentiful,  borne  laterally  from  the 
main  hyphae  on  moderately  short  branches  which  are  of  a  length  less 
than  the  diameter  of  the  oogonium  (rarely)  to  three  times  its  diameter; 
spherical  or  short  pyriform,  usually  48-624  thick,  sometimes  as  small 
as  344;  wall  smooth,  unpitted  except  under  the  antheridia.  Eggs  filling 
the  oogonium,  1-8,  usually  6,  the  diameter  18-244,  some  slightly  flattened 
by  pressure;  eccentric,  with  one  large  oil  drop  outside  the  protoplasm 
when  fully  ripe;  oil  drop  11-144  thick.  Antheridial  branches  slender, 
practically  always  diclinous,  never  arising  from  the  oogonial  stalk  though 
sometimes  the  basal  wall  grows  up  into  the  oogonium  giving  the  ap¬ 
pearance  of  a  thick-walled  hypogynal  antheridium;  simple  or  sparingly 
branched,  sometimes  branching  before  reaching  the  oogonium  and  the 
branches  clasping  different  oogonia.  Antheridia  clearly  abstricted, 
elongated  and  usually  touching  the  oogonia  with  foot-like  projections; 
at  least  one,  usually  more,  on  every  oogonium. 

Found  once  in  Buzzard  Spring,  a  shallow  spring  at  edge  of  bottom 
land  of  Yadkin  River,  near  Yadkin  College,  N.  C.,  March  29,  1921. 
(H.  R.  Totten,  coll.) 

This  well-marked  species,  known  until  now  only  from  Michigan, 
is  apparently  nearest  A.  americana,  from  which  it  clearly  differs  in  the 


PLATE  40 


PLATE  40 
Achlya  Klebsiana 

Fig.  i.  Sporangia  which  have  emptied.  X  167. 

Fig.  2.  Sporangium  emptying  by  two  mouths,  some  spores  having  emerged  from  their 
cysts  inside  and  swimming  actively  (not  half  the  swimming  spores  present  are 
shown).  X  247. 

Fig.  3.  A  gemma  sprouted  into  threads  which  formed  small  sporangia  on  their  tips.  X  73. 

Fig.  4.  Gemmae,  one  of  which  has  sprouted  directly  into  threads  and  one  has  formed  spores 
and  emptied.  X167. 

Fig.  5.  Oogonium  with  antheridium.  X  167. 

Fig.  6.  Sporangia,  one  of  which  has  emptied  as  typical  in  Achlya,  the  other  only  partially 
by  numerous  mouths.  X  108. 

Fig.  7.  Habit  of  sporangia,  the  internodes  longer  than  usual.  X  60. 

Fig.  8.  Mature  egg.  X  720. 

Fig.  9.  Oogonium  with  antheridium  and  ripe  eggs.  X  447. 

Fig.  10.  Sporangium  with  spores  sprouting  in  position.  X  108. 

Fig.  11.  Habit  sketch,  also  showing  emptied  gemmae.  X  108. 

Fig.  12.  Swimming  spores.  X  720. 


PLATE  40 


o  °0^0o 


ACHLYA  KLEBSIANA. 


ACHLYA 


121 


diclinous  antheridia,  longer  oogonial  stalks,  smaller  average  number  of 
eggs  and  unpitted  oogonial  walls  (except  where  the  antheridia  touch). 
With  Pieters’s  description  our  plant  agrees  unusually  well  and  the 
identity  of  our  plants  is  obvious.  Neither  on  flies  nor  on  termites  do  we 
find  a  pronounced  tendency  to  produce  all  the  oogonia  near  the  insect  (as 
Pieters  finds  in  the  case  of  his  form  on  flies),  and  on  corn  meal  agar  our  form 
produces  copious  oogonia  and  antheridia  with  normal  eggs.  Pieters 
says  that  oogonia  were  not  formed  on  the  agar  he  used  (corn  meal  agar 
not  mentioned).  In  fact,  he  found  oogonia  to  be  formed  only  on  flies 
and  in  one  case  on  a  sterilized  pea.  The  oogonia  are  not  very  densely 
set  and,  while  more  numerous  near  the  substratum,  occur  throughout 
the  culture  except  for  a  peripheral  zone  where  the  sporangia  are  being 
formed.  The  species  is  a  very  strong  and  rapid  grower,  is  healthy  and 
reliable  in  ordinary  media  and  forms  oogonia  regularly.  At  room 
temperature  a  culture  made  on  a  fly  at  I  p.  m.  was  discharging  spores 
at  6  p.  m.  the  following  day.  On  corn  meal  agar  in  a  petri  dish  at  room 
temperature  (65-75°  F.)  the  growth  is  at  the  rate  of  nearly  a  centimeter 
a  day.  When  sporangia  discharge  in  agar  they  do  so  only  in  part  and 
the  spores  are  forced  back  in  a  sheath  around  the  sporangium  just  as  is 
shown  for  A.  flagella ta  (plate  37,  fig.  12).  Six  cultures  made  to  test  the 
effect  of  low  temperature  showed  that  in  the  ice  box  (about  io-ii°  C.) 
in  all  cases  oogonia  were  formed  in  immense  quantities  throughout  the 
culture,  while  sporangia  were  very  rare.  In  check  cultures  at  room 
temperature  there  were  produced  large  numbers  of  sporangia  and  far  less 
numerous  oogonia. 

The  spores  vary  in  behavior  as  usual  in  the  genus;  very  often  only 
a  part  emerge  and  not  rarely  all  are  retained.  When  the  spores  escape 
typically  they  emerge  from  their  cysts  and  swim  as  usual,  but  some  or 
all  of  them  are  not  rarely  seen  to  sprout  in  position.  There  is  a  strong 
tendency  in  this  species  for  the  spores  to  emerge  from  more  than  one 
mouth;  (for  other  such  cases  see  A.  caroliniana ,  A.  prolijeroides  and  A. 
flagellata).  Sporangia  with  multiple  mouths  are  of  constant  occurrence 
and  are  not  to  be  confused  with  dictiosporangia  (see  fig. 6).  In  such  cases 
some  of  the  spores  are  nearly  always  left  inside.  One  remarkable  condition 
was  seen  scores  of  times  and  has  not  appeared  so  strikingly  in  any  other 
Achlya.  The  retained  spores  emerged  from  their  cysts  inside  the  spor¬ 
angium  and  swam  very  actively  inside  it,  none  ever  getting  out  even 
though  the  opening  was  free.  In  a  number  of  cases  in  which  nearly 
all  the  spores  were  retained  they  behaved  in  this  way  and  the  sporangia 
presented  a  novel  sight  with  hundreds  of  spores  swimming  rapidly  in  a 
crowded  swarm.  In  such  cases  the  empty  cysts  were  soon  dissolved,  leaving 
the  space  free.  After  coming  to  rest  inside  the  sporangium  many  of  these 


]  22 


THE  SAPROLEGNIACEAE 


spores  sprout  in  position,  most  of  the  sprouts  remaining  inside  the  spor¬ 
angium,  others  emerging  through  the  opening  or  directly  through  the  wall. 
No  well-developed  dictiosporangia  have  been  seen  in  our  cultures,  but 
when  the  spores  are  all  retained  in  the  sporangium  a  few  of  the  peripheral 
ones  may  emerge  exactly  as  in  Dictyuchus,  the  majority  emerging  from 
their  cysts  to  swim  inside  as  described  above.  Sporangia  of  the  A  planes 
type  with  all  the  spores  retained  and  sprouting  with  germ  tubes  through 
the  sporangium  wall  are  not  rare  (fig.io),  but  the  tubes  are  not  vigorous 
in  such  cases  and  soon  die. 

12.  Achlya  caroliniana  Coker.  Bot.  Gaz.  50:  381.  1910. 

Plate  41 

Hyphae  rather  stout,  about  484  thick  at  the  base  and  204  near  the 
tip,  in  strong  cultures  reaching  a  length  of  1.5  cm.  Sporangia  irregularly 
cylindrical,  about  20-304  in  diameter,  often  discharging  by  several  open¬ 
ings,  sometimes  remaining  closed  and  emptying  as  in  Dictyuchus,  cili¬ 
ated  on  emerging  but  behaving  as  in  other  Achlyas.  Spores  11-124  in 
diameter,  most  about  11.24.  Oogonia  abundant,  very  small,  24-554  thick, 
most  about  30-374,  spherical  when  terminal,  wall  smooth,  or  not  rarely 
with  one  or  two  papillae  or  angles,  thin,  not  pitted,  light  yellow  in  age, 
terminating  short  or  moderately  long,  slender  branches,  which  are  racemose- 
ly  borne  on  the  strong  main  hyphae,  or  rather  rarely  intercalary  and  elon¬ 
gated,  at  times  filiform  with  several  elongated  eggs  in  a  row.  Oogonial 
branches  generally  simple,  but  often  giving  off  near  the  base,  or  sometimes 
near  the  oogonia,  one  or  two  branches  w-hich  also  terminate  in  oogonia, 
and,  as  a  rule,  are  curved  downward.  Eggs  generally  1-2,  not  rarely 
4,  eccentric,  with  a  large  oil  globule,  18.5-234  in  diameter,  averaging 
about  22 4,  often  elongated  by  pressure.  Antheridia  absent.  A  papilla, 
thick- walled  and  soon  empty,  often  gnrvvs  into  the  oogonium  through  the 
basal  partition  exactly  as  in  other  members  of  the  Prolifer  a  group  and  in 
A.  hypogyyia. 

Distinguished  by  the  absence  of  antheridia  and  by  the  small,  un¬ 
pitted  oogonia  with  a  few  small  eggs. 

Rare  in  pools  and  small  streams,  such  as  Arboretum  branch,  Battle’s 
branch,  small  pools  in  pasture  belovr  Purefoy’s  Mill,  etc.  Appeared  five 
times  in  Chapel  Hill  collections  before  December  15, 1913  (see  table  on  p.  14). 

This  species  is  particularly  interesting  in  that  it  is  the  only  species 
in  the  Prolifera  group  without  antheridia.  It  is  almost  exactly  like  A.  im¬ 
perfecta  in  other  v'ays  (except  for  absence  of  pits). 

The  cultures  in  the  following  experiments  vrere  made  from  a  pure 
culture  on  corn  meal  agar  of  No.  10  of  March  20,  1913,  using  egg  yolk 
as  the  food  material: 

In  .1%  KNO3.  Limited  growth  of  rather  coarse,  strong  hyphae,  as  in  the  following  three 
experiments.  Sporangia  present.  Oogonia  on  smaller  hyphae,  but  eggs  not  maturing. 


PLATE  41 


PLATE  41 

Achlya  caroliniana 

Fig.  i.  Oogonia  with  papillae.  X  503. 

Fig.  2.  Young  oogonia  and  sporangia.  X  188. 

Fig.  3.  Gemma  and  three  sporangia  which  were  gemmae.  X  122. 

Fig.  4.  Habit  of  oogonia.  X  188. 

Fig.  5.  Sporangium  with  spores  clustered  at  tip.  X  251. 

Fig.  6.  Oogonium  with  an  ingrowth  from  below.  X  503. 

Fig.  7.  Two  odd-shaped  intercalary  oogonia  containing  ripe  eggs.  X  503. 

Fig.  8.  Empty  sporangia,  gemmae  and  young  oogonia.  X  188. 

Fig.  9.  Sporangium  partly  filled  with  spores  and  odd-shaped  oogonia.  X  188. 


PLATE  41 


ACHLYA  CAROTIN  I  ANA 


1  •  . 


ACHLYA 


123 


In  .1%  KH2PO4.  Rather  short,  but  very  stout  growth.  A  good  number  of  large  and 
irregular  and  often  branched  sporangia,  forming  very  many  spores,  and  some  generally 
remaining  inside.  The  spores  on  emerging  do  not  stick  to  sporangium,  but  fall  to 
bottom  in  open  order. 

In  .1%  NaH2P04.  Strong  and  very  stout  growth.  A  good  many  large  sporangia,  often 
irregular  and  with  more  than  one  mouth,  usually  some  spores  remain  inside.  Many 
oogonial  initials,  most  of  which  were  smooth,  but  some  spiny;  none  matured  eggs. 
Some  of  the  hyphae  had  a  diameter  of  964.  Some  of  the  large  threads  were  segmented 
up  into  dense,  rather  short  fragments. 

In  .1%  K2SO4.  About  1  inch  growth.  Hyphae  very  strong,  as  in  preceding.  No  spor¬ 
angia.  A  number  of  oogonia,  but  no  good  eggs  maturing. 

In  .1%  Ca-^PChfi.  About  I  inch  growth.  Very  large  hyphae.  Immense  number  of 
oogonia,  with  1-3  or  4  eggs  each.  Sporangia  present,  but  not  numerous.  The  great 
majority  of  the  oogonia  were  quite  spherical  and  without  spines.  Some,  however, 
had  distinct  and  even  numerous  spines.  More  large  oogonia  with  4  eggs  than  before 
seen. 

In  .1%  Ca(N03)2.  Stout  growth,  but  not  so  extensive  as  in  others.  Almost  no  sporangia. 
Many  oogonia  remarkable  for  their  very  long  stalks,  2,  3  or  4  times  longer  than  usual, 
giving  the  culture  a  very  peculiar  appearance.  The  stalks  massive,  simple  and  straight. 
A  good  many  good  eggs  formed. 

In  .1  %  K3P04.  No  growth. 

On  corn  meal  agar.  Growth  vigorous,  covering  dish.  Many  enlarged  and  denser  ends  oi 
stout  hyphae  becoming  cut  up  in  rows  of  sections  to  form  gemmae.  Locally  there  were 
found  also  a  good  many  oogonia  of  perfectly  normal  appearance  and  with  1  or  2  good 
eggs,  almost  all  spiny. 

The  following  experiments  were  made  to  test  the  best  method  of 
preserving  live  cultures: 

Culture  put  in  vial  on  corn  meal  agar,  vial  closed  with  a  plug  of  cotton  and  placed  in  a 
dark  chamber  in  May,  1913.  When  tested  in  December,  1913,  it  was  found  to  be 
alive. 

Culture  put  in  distilled  water  November  18,  1909.  When  tested  on  September  22,  1917,  it 
was  found  to  be  dead. 

13.  Achlya  apiculata  deBary.  Bot.  Zeit.  46:  635,  pi.  10,  figs.  3-5.  1888. 

Plates  42  and  43 

Vegetative  growth  ample  and  abundant,  but  not  so  stout  as  in 
A .  oblongata  or  in  the  Prolijera  group.  The  main  filaments  mostly  about 
40-604  thick,  tips  rounded;  breaking  up  soon  after  maturity  into  seg¬ 
ments  with  little  or  no  change  in  the  appearance  of  the  threads,  each 
segment  becoming  a  gemma  and  resting  indefinitely  until  the  condi¬ 
tions  change,  then  forming  spores  like  sporangia.  Sporangia  moder¬ 
ately  plentiful,  long  or  short,  usually  somewhat  larger  than  the  threads 
and  gradually  pointed  towards  the  end,  emptying  as  usual  for  an  Achlya, 
or  often  remaining  closed  and  emptying  as  in  Dictyuchns.  Spores  cili¬ 
ated  on  emerging  and  capable  of  swimming  under  certain  conditions 
(see  notes  under  experiments),  12.5—14.54  in  diameter  or  at  times  larger. 
Oogonia  not  formed  regularly  or  abundantly  except  at  low  temperatures, 
racemosely  borne  on  the  tips  of  short  or  rather  long  branches  which 


124 


THE  SAPROLEGN I ACEAE 


are  usually  bent  and  sometimes  make  a  complete  turn,  rarely  interca¬ 
lary,  ovate,  short  pyriform  or  spherical,  at  low  temperatures  very  rarely 
formed  within  empty  sporangia  (as  in  Sap  role gnia  ferax),  typically  with 
(but  often  without)  a  more  or  less  prominent  apiculus;  60-119’j.  thick, 
most  about  8o;jl;  walls  thin,  smooth,  unpitted.  Eggs  few,  large,  very  dark, 
subcentric,  1-5,  usually  2  or  3  (rarely  10),  25-40’j.  thick,  sometimes 
larger,  average  about  36:0..  Antheridial  branches  usually  androgynous, 
but  often  diclinous,  arising  from  the  main  hyphae  or  from  the  oogonial 
branches,  soon  becoming  inconspicuous.  Antheridia  small,  tuberous  or 
cylindrical,  usually  one  or  more  to  each  oogonium. 

The  species  is  plentiful,  especially  in  winter  and  spring,  in  branches, 
outlets  of  springs,  edges  of  meadows,  etc.,  as  in  Arboretum  spring  and 
branch,  Battle’s  spring  and  branch,  Glen  Burnie  meadow.  We  find  it 
also  at  Tarboro,  N.  C.  (March  7,  1921).  Collected  94  times  between 
February  15,  1912,  and  December  12,  1913  (see  table  on  p.  14),  and  often 
since.  Reported  heretofore  in  America  only  by  Humphrey  from  Massa¬ 
chusetts  and  by  Atkinson  from  Alabama.  For  other  illustrations  see  Ward 
(’83),  pi.  22,  figs.  15  and  16;  Humphrey  (’92),  pi.  15,  figs.  26  and  27;  pi. 
19,  figs  82-86. 

A  single  antheridial  branch  may,  on  reaching  the  oogonium,  branch 
so  extensively  as  to  net  the  whole  surface,  but  frequently  no  proper 
antheridium  is  cut  off,  and  the  embracing  processes  are  not  very  densely 
filled  with  protoplasm.  As  in  A.  oblongata  the  eggs  go  to  pieces  so 
soon  that  it  is  exceptional  that  the  final  structure  of  maturity  is  reached. 
The  homogeneous  and  almost  black  appearance  of  youth  (transmitted 
light)  gradually  becomes  more  granular  and  lighter.  Just  before  disor¬ 
ganizing  the  structure  is  that  of  a  large  central  globule  nearer  one  side  than 
the  other  and  apparently  protoplasmic,  completely  surrounded  by  darker, 
rather  dimly  defined  fatty  globules.  This  agrees  very  well  with  deBary’s 
description  and  figure  except  that  he  considered  the  central  mass  as  a 
fat  globule.  In  both  this  species  and  its  variety  prolijica  the  oogonial 
apiculus  when  present  is  not  the  result  of  an  outgrowth  from  a  spherical 
oogonial  initial,  but  represents  the  unswollen  tip  of  the  original  branch 
which  produced  the  oogonium  by  an  inflation  below.  If  the  tip  is  rather 
long  the  oogonia  tend  to  be  somewhat  oval. 

The  spores  develop  exactly  as  described  for  Saprolegnia  anisospora. 
The  spore  units  appear,  then  disappear  again  about  five  or  ten  minutes 
before  emergence,  then  gradually  reappear,  but  with  less  clear  outline, 
then  the  entire  spore  mass  is  slightly  drawn  away  from  the  walls  (most 
noticeable  in  A.  apiculata  in  basal  part,  but  to  be  made  out  all  over), 
and  the  discharge  occurs  in  a  few  minutes.  The  whole  spore  mass 
holds  closely  together  and  makes  a  central  column,  emerging  as  one 
body,  with  no  individual  motion  visible,  thus  showing  without  any  doubt 


PLATE  42 


PLATE  42 


Achlya  apiculata 

Fig.  I.  Cylindrical  and  spherical  oogonia.  X  167. 

Fig.  2.  A  dictiosporangium,  with  one  of  the  spores  sprouting  into  a  filament.  X  447. 

Fig.  3.  Habit  of  oogonia  and  antheridia.  X  102. 

Fig.  4.  Sporangia,  several  in  serial  arrangement  in  same  hypha.  X  100. 

Fig.  5.  Spore  emerging  from  cyst.  X  720. 

Fig.  6.  A  mature  egg.  X  447. 

Fig.  7.  Gemmae.  X  107. 

Fig.  8.  A  small  dictiosporangium.  X  167. 

Fig.  9.  Peculiar  case  in  which  an  oogonial  initial  was  halted  and  sent  off  an  antheridial 
branch.  X  167. 

Fig.  10.  Oogonia.  X  247. 

Fig.  11.  Sporangia,  one  on  left  a  dictiosporangium  with  the  spores  emerged  but  not  swim¬ 
ming;  one  in  center  containing  four  sprouting  spores.  X  60. 

Fig.  12.  An  intercalary  oogonium.  X  247. 

Fig.  13.  Sporangia  and  oogonium  with  androgynous  antheridium.  X  167. 

Fig.  14.  An  intercalary  oogonium  with  a  papilla.  X  247. 


PLATE  42 


ACHLYA  APICULATA 


PLATE  43 


PLATE  43 
Achlya  apiculata 


Fig.  i.  A.  apiculata,  showing  usual  habit  of  oogonia.  (Compare  Fig.  4  below).  X  68. 

Achlya  apiculata  var.  prolifica 

Fig.  2.  Oogonium  inside  sporangium.  X  122. 

Fig.  3.  Oogonia  and  antheridia.  X  1 1 7. 

Fig.  4.  Habit  of  oogonia  and  antheridia,  showing  relative  number  as  compared  with 
A.  apiculata.  X  1 1 7. 

Fig.  5.  Cylindrical  oogonia  in  a  sporangium.  X  278. 

Fig.  6.  Peculiar  and  characteristi :  tips  of  threads  of  vegetative  hyphae.  X  112. 

Fig.  7.  Egg  structure  and  peculiar  internal  wall.  Oogonium  with  unevenly  thickened 
wall  and  single  mature  egg  of  typical  structure.  X  1012. 


TV  V  ,'X  » 


PLATE  43 


ACHLYA  APICULATA.  FIG.  i. 


ACHLYA  APICULATA  VAR.  PROLIFICA.  FIGS.  2-7. 


ACHLYA 


125 


that  the  spores  are  expelled  by  internal  pressure.  In  some  cultures  the 
spores  will  run  larger  in  a  good  many  of  the  sporangia  without  apparent 
cause,  for  example,  in  No.  2  of  December  12,  1913,  they  were  at  times 
14.8-l6.6ix  in  diameter. 

Dictiosporangia  have  been  seen  a  number  of  times,  e.g.,  in  No.  6 
of  January  7,  1914.  In  some  cases  oogonia  are  attached  immediately 
below  the  dictiosporangia  (pi.  42,  fig.  10). 

Oogonial  reproduction  is  rarely  either  frequent  or  abundant  in  this 
species,  and  in  some  collections  this  tendency  towards  sterility  is  carried 
to  an  extreme  (see  under  experiments  below). 

In  a  culture  on  a  mushroom  grub  in  water  from  the  Arboretum  spring 
a  sporangium  was  made  to  discharge  under  a  cover  glass.  The  spore  mass 
broke  up  in  part  and  a  good  many  of  the  outer  spores  were  carried  to  a 
little  distance  and  scattered,  and  their  slight  individual  rocking  motion 
could  much  more  easily  be  seen.  Iodine  when  added  clearly  demon¬ 
strated  the  cilia. 

At  one  time  spores  were  seen  to  emerge  from  their  cysts  at  room 
temperature  (about  720  F.)  in  about  5  hours  after  discharge,  the  emergence 
occupying  about  2  minutes.  Most  of  the  cysts  were  about  I3.5;x  in  diam¬ 
eter,  often  with  larger  ones  in  the  same  sporangium,  the  latter  mostly 
about  22.5^  in  diameter,  and  apparently  the  bulk  of  four  ordinary  spores. 
These  latter  on  emerging  have  several  sets  of  cilia.  After  emerging 
the  spores  scarcely  rock  for  several  minutes,  then  slowly  rock,  and  finally 
after  more  active  rocking  get  away  rather  sluggishly  after  about  5-8 
minutes.  Most  are  about  12  x  14.5^  in  last  stage. 

The  eleven  following  cultures  were  made  from  No.  4  of  Novem¬ 
ber  25,  1912: 

In  agaricus  broth.  Made  a  good  start,  but  soon  destroyed  by  an  immense  growth  of 
bacteria. 

In  egg  yolk  broth.  A  delicate  growth,  the  hyphae  soon  losing  their  contents  except  for  the 
cut  off  tips,  which  look  like  small  resting  sporangia.  Hyphae  encrusted  with  amor¬ 
phous  granules.  Bacteria  not  noticeable. 

In  equal  parts  maltose  5%  and  peptone  .01%.  Grew  rather  slowly  to  about  ^  inch  in 
diameter,  then  became  unhealthy  and  died.  No  reproductive  bodies. 

On  fly  in  jar  of  distilled  water.  Th  water  was  about  one  inch  deep  and  the  fly  sank  to  the 
bottom.  Growth  was  very  stout  and  bold — one  inch  in  diameter.  The  hyphae 
branched  very  little  and  all  ended  in  sporangia,  very  few  of  which  discharged  their 
spores  completely.  The  majority  did  not  open  at  all.  Many  of  the  spores  sprouted 
in  position,  and  grew  to  some  length.  No  other  reproductive  bodies. 

On  corn  meal  agar.  Grew  well,  covering  agar,  but  no  reproductive  bodies  were  formed. 
Hyphae  gradually  became  colorless,  and  formed  cross  walls  at  places,  segregating  seg¬ 
ments  of  denser  material.  After  about  one  month  a  test  was  made  and  the  culture 
found  to  be  dead,  even  the  denser  sections. 


126 


THE  SAPROLEGNIACEAE 


On  corn  meal  egg  yolk  agar.  Grew  vigorously  but  did  not  cover  dish.  A  pretty  dense 
growth  of  aerial  hyphae  was  formed  and  reached  the  lid  — looked  much  like  Mucor. 
No  reproduction. 

In  the  following  five  experiments  equal  parts  of  a  .2%  solution 
in  distilled  water  of  the  salts  indicated  was  used;  the  food  material  being 
yolk  of  egg: 

In  KH2PO4.  Stout,  healthy  growth.  No  reproduction. 

In  NaH2P04.  Good  growth.  No  reproduction. 

In  K2SO4.  Poor  growth.  No  reproduction.  Hyphae  incrusted  with  amorphous  granules. 
In  Ca3(P04)2.  Strong,  vigorous  growth.  No  reproduction. 

In  Ca(N03)2.  Strong  but  limited  growth.  A  good  many  sporangia,  some  emptying  nor¬ 
mally,  most  with  spores  sprouting  in  position. 

The  six  following  cultures  were  made  from  No.  12  of  March  6, 
1913: 

On  egg  yolk  in  distilled  water  +  1  drop  of  lactic  acid  to  100  c.c.  Growth  very  strong  and 
healthy,  consisting  of  large  and  little  branched  hyphae.  Sporangia  sparingly  produced, 
long  and  pointed,  discharging  in  most  cases.  Spores  sprouting  in  position  in  some 
cases.  No  other  reproduction.  No  noticeable  bacteria. 

On  egg  yolk  in  distilled  water  +  1  drop  of  lactic  acid  in  200  c.c.  Growth  as  in  the  preced¬ 
ing  experiment,  except  not  quite  so  strong  and  no  sporangia  or  any  other  reproduction. 
No  noticeable  bacteria. 

On  boiled  potato  tuber  and  sprout  in  potato  broth.  No  growth. 

On  boiled  potato  tuber  and  sprout  in  distilled  water.  Fair  growth  of  limited  extent,  bac¬ 
teria  present  and  apparently  interfering.  Tips  of  hyphae  often  dying  and  the  thread 
extended  by  growth  from  below,  as  is  frequent  in  this  species.  No  sporangia  or  other 
reproduction. 

On  egg  yolk  in  distilled  water.  Growth  fairly  good,  but  no  sporangia  or  other  reproduction. 
Not  foul  with  bacteria. 

On  egg  yolk  in  3%  cane  sugar  in  distilled  water.  Growth  strong,  somewhat  contorted, 
only  a  few  sporangia,  and  spores  sprouting  at  the  tip. 

The  following  experiment  was  made  to  test  the  resistance  to  cold : 

A  strong  culture  was  left  outside  on  window  sill  and  was  frozen  hard  (temperature  23°F.). 

The  culture  was  killed. 

The  following  experiments  were  made  to  test  the  best  method  of 
preserving  live  cultures: 

A  culture  (No.  6  of  April  19,  1913)  put  in  vial  on  corn  meal  agar  in  the  spring  of  19 1 3  was 
found  to  be  dead  December  I,  1913. 

Pure  culture  (No.  4  of  November  25th,  1912)  was  put  in  an  aquarium  jar  with  algae  on 
laboratory  table  on  February  19,  1913.  No  growth  resulted  when  tested  on  Septem¬ 
ber  18,  1917. 

The  following  experiment  is  typical  of  many  made  to  determine  the 
effect  of  cold  on  the  formation  of  reproductive  organs: 

On  piece  of  boiled  corn  grain  in  sterile  well  water  in  ice  box  temperature  from  120  to  20° 
C.  Growth  good  and  many  normal  oogonia  formed,  but  only  about  a  fifth  as  many 
as  in  the  var.  prolifica  in  the  same  circumstances;  no  sporangia. 


ACHLYA 


I2J 


14.  Achlya  apiculata  var.  prolifica  Coker  and  Couch  n.  var. 

Plates  43  and  50 

Growth  fairly  dense  but  only  moderately  long,  reaching  a  length  of 
0.3-0. 4  cm.  (on  termite  ants  or  mushroom  grubs).  Main  hyphae  branch¬ 
ing  considerably,  rarely  up  to  904  close  to  base;  the  tips  of  hyphae  pointed 
and  hyaline  when  young,  drying  or  becoming  rounded  with  maturity. 
In  summer  (room  temperature  of  2 1-32. 50  C.)  the  ends  of  the  hyphae 
become  elaborately  branched  and  the  tips  considerably  swollen.  Spor¬ 
angia,  spores  and  gemmae  as  in  A.  apiculata,  but  the  gemmae  less  num¬ 
erous.  Oogonia  produced  in  all  cultures,  at  low  temperature  (12-20°  C.) 
in  great  abundance,  but  at  room  temperature  (21-30°  C.)  usually  few 
and  sometimes  none;  diameter  40-904,  in  most  55-65-4,  spherical,  less 
often  oblong  or  rarelyr  cylindrical  in  old  sporangia  as  in  Saprolegnia 
ferax,  quite  often  provided  with  a  short  apiculus,  rarely  with  a  long  one. 
Walls  smooth  and  unpitted  except  where  the  antheridia  touch;  however, 
in  old  cultures  on  corn  grain  the  wall  may  be  considerably  roughened 
but  not  typically^  pitted  (pi.  43, fig.  7).  Oogonial  stalks  as  in  A.  apiculata 
except  more  branched.  Eggs  usually  1  or  2,  rarely  as  many  as  5;  antherid- 
ial  branches,  antheridia  and  the  structure  of  the  egg  the  same  as  in  the 
species. 

This  plant  appeared  once  (No.  2  of  February  28,  1921,  in  branch  in 
Latta’s  Woods)  among  more  than  300  collections  made  around  Charlotte 
N.  C.,  by  J.  N.  Couch. 

The  present  variety  in  vegetative  growth  and  in  the  shape  and  size 
of  the  sporangia  and  spores  is  indistinguishable  from  the  species.  The 
oogonial  stalks  of  both  plants  are  quite  similar,  though  the  stalks  of  the 
variety  show  a  stronger  tendency  to  branch  than  in  the  species.  Apic- 
ulate  oogonia  are  found  in  both  plants  but  oogonia  with  such  outgrowths 
are  more  abundant  in  the  variety.  The  outstanding  differences  between 
the  two  plants  are  found,  first,  in  the  regularity  with  which  our  present 
plant  bears  sexual  fruits  even  in  room  temperature  (17-240  C.),  while  A. 
apiculata  fruits  very  poorly  in  the  laboratory;  second,  in  the  relative 
number  of  oogonia  produced  under  the  optimum  temperature  for  both 
plants,  the  number  being  about  five  times  greater  in  the  variety  than  in 
A.  apiculata ;  third,  in  the  comparative  size  of  the  oogonia,  the  average 
diameter  in  the  variety  being  between  55  and  654  while  in  the  species  the 
average  diameter  is  between  70  and  804;  and  fourth,  in  the  relative  nu  mber 
of  eggs  in  the  oogonia,  the  usual  number  in  the  variety  being  1  or  2,  rarely^ 
5,  while  in  A.  apiculata  the  usual  number  is  between  3  and  5,  rarely  10. 
This  variety  is  the  only  member  of  the  Saprolegniaceae  in  which  we  have 
been  able  to  observe  sprouting  eggs.  Old  eggs  from  a  culture  made  August 

15,  1921,  were  put  on  corn  meal  agar  in  February^,  1922.  In  forty-eight 
hours  theyr  had  sprouted  to  form  long,  branched  threads. 


128 


THE  SAPROLEGNIACEAE 


The  following  experiments  are  typical  of  many  made  to  determine 
the  effects  of  temperature  on  the  production  of  sexual  organs. 

On  termite  ants  in  sterile  well  water  in  ice  box.  Temperature  ranging  from  1 2°  C.  to  20°  C. 
Growth  good,  5  cm.  long.  A  good  many  sporangia  formed  and  emptied,  and  a  good 
many  oogonia,  some  of  them  in  empty  sporangia  as  in  several  previous  cultures 
on  ants  in  ice  box.  Oogonia  with  very  long  stalks. 

On  termite  ants  in  sterile  well  water  in  room.  Temperature  ranging  from  17 °-22°C.  Growth 
good,  the  ends  of  hyphae  considerably  branched,  swollen  and  contorted;  many  spor¬ 
angia  and  a  fair  number  of  oogonia. 

On  termite  ants  in  sterile  well  water  in  room.  Temperature  ranging  from  21 0  to  32. 50  C. 
Growth  very  poor,  bacteria  bad.  Two  days  later  dead. 

On  piece  of  boiled  corn  grain  in  sterile  well  water  in  ice  box.  Temperature  from  i2°-20° 
C.  Growth  very  good,  mycelium  dense,  threads  much  branched  and  curled.  Many 
sporangia,  a  large  number  of  which  had  emptied;  very  many  oogonia  close  to  periphery 
of  mycelium,  oogonial  stalks  much  curled  and  branched  as  also  the  antheridial  stalks. 
Oogonia  average  by  count  about  five  times  as  many  in  a  given  field  as  in  the  species. 

On  piece  of  boiled  corn  grain  in  sterile  well  water  in  room.  Temperature  170— 22°  C.  Growth 
good,  the  ends  of  hyphae  considerably  branched,  swollen  and  contorted ;  many  sporangia, 
and  a  fair  number  of  oogonia. 

O11  piece  of  boiled  corn  grain  in  sterile  well  water  in  room.  Temperature  2i°-32.5°  C. 
Growth  good,  but  soon  interfered  with  and  killed  by  bacteria. 


15.  Achlya  megasperma  Humphrey.  Trans.  Amer.  Phil.  Soc.  17:  118. 
pi.  18,  hgs.  74-77*  1892  [1893]. 

Plate  44 

Mycelium  slenderer  than  in  most  Achlyas.  Sporangia  very  abundant, 
of  the  typical  Achlya  type,  borne  singly  or  in  clusters  (often  as  many 
as  eight)  on  the  ends  of  hyphae,  varying  much  in  shape  from  the  long, 
slender,  tapering  sporangia  of  Achlya  apiculata  to  a  club-shaped  form 
swollen  at  the  distal  end;  100-10004  long,  most  between  300  and  4004. 
Spores  1 1  [a  in  diameter.  Gemmae  developed  in  considerable  abundance, 
either  single  and  shaped  like  a  sporangium  with  pointed  tip  or  very 
elaborately  branched ;  when  solitary  often  separating  from  the  hypha  and 
falling  to  the  bottom.  Oogonia  racemosely  borne  on  branches  which  are 
about  as  long  as  or  shorter  than  the  thickness  of  the  oogonia;  rarely  the 
oogonial  branches  may  be  longer.  Oogonia  without  an  apiculus,  usually 
spherical,  occasionally  oblong,  rarely  cylindrical,  60-1194  thick,  usually 
between  70  and  804,  oogonial  wall  thickened  and  without  pits  except 
for  thin  places  under  the  antheridia.  Eggs  1-10  or  rarely  more,  usually 
2-5,  almost  or  entirely  filling  the  oogonium,  often  elliptic  from  pressure; 
39-664  thick,  usually  between  42  and  524  (in  an  oogonium  in  which  there 
were  9  eggs  the  average  size  was  44.14);  structure  subcentric  and  exactly 
as  in  A.  apiculata-,  walls  3-4.64  thick.  Antheridial  branches  diclinous 
or  androgynous  but  never  arising  from  the  oogonial  stalk,  usually  di¬ 
clinous,  often  much  branched  and  not  applied  to  oogonia;  long  and  very 
slender,  becoming  barely  visible  after  the  eggs  are  formed.  Antheridia 
tuberous  and  fairly  conspicuous;  usually  one  or  two  on  each  oogonium; 
not  rarely  absent. 


PLATE  44 


PLATE  44 
Achlya  megasperma 

Figs.  ,  2,  3,  4.  Gemmae,  one  of  which  has  become  a  sporangium. 
Fig.  5.  Normal  sporangium.  X  103. 

Fig.  6.  Habit  sketch.  X  55. 

Fig.  7.  Habit  sketch.  X  103. 

Fig.  8.  A  cylindrical  oogonium.  X  247. 

Fig.  9.  An  elaborately  branched  gemma.  X  103. 

Fig.  10.  Oogonium  showing  surface  view  of  eggs.  X  433. 

Fig.  11.  Oogonium  with  peculiar  stalk.  X  247. 

Fig.  12.  Oogonium  showing  optical  section  of  eggs.  X  433. 

Fig.  13.  Large  oogonium  containing  ten  eggs.  X  247. 


X  103. 


PLATE  44 


ACHLYA 


129 


This  plant  with  its  large  eggs  reminds  one  of  A.  apiculata,  but  by 
careful  observations  and  measurements  it  is  found  to  differ  from  the 
latter  in  the  following  ways:  the  eggs  average  about  44’i.  thick;  the 
oogonial  stalks  are  short  and  straight;  the  oogonial  walls  are  thickened 
and  without  an  apiculus,  and  the  oogonia  are  closely  packed  with  eggs. 
In  A.  apiculata  the  eggs  average  about  36(0.;  the  oogonial  stalks  are  long 
and  curved;  the  oogonial  walls  thin;  and  the  oogonia  only  about  half 
filled  with  eggs.  These  characters  while  separating  the  present  plant 
from  A.  apiculata  at  the  same  time  identify  it  as  A.  megasperma. 

Humphrey  found  the  plant  only  once  and  then  in  cultures  from 
Spirogyra,  dead  leaves,  etc.,  taken  from  a  boggy  spot  by  a  small  brook. 
Our  plant  also  has  been  collected  but  once,  near  Charlotte,  N.  C.,  by 
J.  N.  Couch,  February  12,  1921,  and  from  a  situation  similar  to  that  in 
which  Humphrey  found  it.  Mr.  Couch  has  prepared  the  accompanying 
plate. 

16.  Achlya  polyandra  Hildebrand.  Jahrb.  f.  wiss.  Bot.  6:  258.  pi.  16, 
figs.  7-1 1.  1867. 

?  Achlya  gracilipes  deBary.  Bot.  Zeit.  46:  635,  pi.  10,  figs.  2  and  6. 
1888. 

Plate  53 

This  species  has  been  reported  in  America  only  from  Massachusetts 
(Am  herst)  by  Humphrey  (’92,  p.  119)  and  from  Michigan  by  Pieters  (in 
Kauff  man,  ’06).  It  is  distinguished  by  the  subcentric  (?)  eggs,  the  ab¬ 
sence  of  pits  in  the  oogonial  walls,  the  rather  long  stalks  of  the  oogonia, 
and  by  the  androgynous  antheridia  which  spring  as  a  rule  from  the 
original  stalks.  We  take  the  following  description  from  Humphrey: 

“Hyphae  stout,  long.  Zoosporangia  often  not  abundant,  secondary 
ones  rare,  nearly  cylindrical.  Oogonial  branches  usually  very  long  and 
often  recurved  at  the  tip,  racemose.  Oogonia  terminal,  globular,  with 
smooth  and  unpitted  walls.  Antheridial  branches  arising  chiefly  from 
the  oogonial  branches  not  far  from  the  oogonia,  often  branched.  An¬ 
theridia  one  to  several  on  each  oogonium,  short-clavate.  Oospores  5  to 
25,  usually  10  to  15,  in  an  oogonium,  centric,  their  average  diameter 

Humphrey  thought  that  A.  gracilipes  deB.  and  A.  polyandra  Hildb. 
were  the  same,  but  Pieters  suggests  that  his  figures  of  the  European 
plant  (figs.  1-4)  are  exactly  like  those  of  A.  gracilipes  deB.  and  that 
that  may  be  a  good  species,  different  from  A.  polyandra.  (It  is,  how¬ 
ever,  to  be  observed  that  in  Pieters’s  figures  the  original  stalks  are  not 
recurved  at  the  tips  as  in  A.  gracilipes.)  Fischer  regards  Hildebrand’s 
plant  as  probably  intermediate  between  A.  gracilipes  and  A.  polyandra 
deB.  It  seems  to  us  probable,  however,  that  Humphrey  is  correct. 
It  will  be  noticed  that  both  deBary  and  Hildebrand,  as  well  as  Humph- 


1 30 


THE  SAPROLEGNIACEAE 


rey  and  Pieters,  show  the  eggs  not  by  any  means  filling  the  oogonia. 
Pieters  does  not  mention  or  show  the  internal  structure  of  the  eggs  in  the 
plant  he  studied.  For  other  illustrations  see  Massee  (’19),  pi.  2,  fig.  31. 

Fertilization  occurs  in  this  species,  as  Trow  has  shown  in  his  1904 
paper,  with  about  the  same  phenomena  as  he  demonstrates  in  more 
detail  for  A.  deBaryana.  Trow,  however,  does  not  claim  positively  for 
this  species  a  second  division  of  nuclei  in  the  oogonium  before  egg  form¬ 
ation.  It  is  unfortunate  that  he  gives  no  new  data  on  the  structure 
of  the  mature  eggs.  It  probably  is  almost  like  that  of  A.  apiculata. 
DeBary  describes  the  eggs  of  A.  gracilipes  as  “centric,”  but  his  figures  do 
not  show  the  structure. 

Working  at  least  in  part  on  A.  gracilipes,  Scerbak  (1910)  tested 
the  effect  on  diplanetism  of  various  external  conditions  and  found  the 
second  swimming  stage  could  be  inhibited  by  osmotic  pressure  of  the 
medium  and  under  the  influence  of  narcotics,  etc.  The  paper  is  in 
Russian  and  only  a  short  paragraph  in  German  gives  the  conclusion. 

We  quote  the  following  discussion  of  synonymy  by  Humphrey 

(p.  1 19): 

“It  [A.  polyandra  Hildb.]  is  especially  interesting  as  having  been 
the  subject  of  a  misunderstanding  which  has  led  to  a  confusion  in  syn¬ 
onymy  that  I  have  here  attempted  to  correct.  It  was  undoubtedly 
this  species  which  Hildebrand  described  (’67)  as  A.  polyandra.  As 
has  been  already  pointed  out,  deBary  gave  the  same  name  (’81)  to  a 
distinct  species  which  he  recognized  as  differing  from  Hildebrand’s  de¬ 
scription,  but  thought  to  be  probably  his  species.  At  the  time  of  the 
completion  of  the  paper  quoted  deBary  had  probably  never  seen  this 
form,  as  his  later  paper  (’88)  states  that  he  first  obtained  it  in  January 
of  1881,  the  year  of  the  publication  of  the  earlier  one.  And  while  he 
did  study  it,  he  failed  to  notice  its  correspondence  with  Hildebrand’s 
figures  and  description,  and  therefore  named  it  anew  A.  gracilipes.  But 
no  one  who  will  carefully  compare  the  figures  given  by  both  authors 
will,  I  think,  seriously  question  that  they  represent  the  same  species. 
Again,  Hildebrand  states  that  secondary  sporangia  are  not  produced  in 
his  A.  polyandra,  a  statement  that  deBary  (’81)  disputes  as  untrue  for 
his  A.  polyandra.  But  in  his  description  of  A.  gracilipes  (’88),  deBary 
says  that  secondary  sporangia  are  only  sparingly  developed,  a  statement 
which  I  can  corroborate  for  American  specimens.  The  two  descriptions 
agree  in  all  other  essential  points,  so  far  as  they  are  comparable;  and 
the  evidence  seems  completely  satisfactory  that  the  correct  synonymy 
of  this  distinct  species  is  as  above  given.” 


ACHLYA 


131 


17.  Achlya  conspicua  n.  sp. 

Plates  45  and  46 

Hyphae  long  and  more  stout  than  in  most  Achlyas,  up  to  1664 
thick  near  base  or  some  as  small  as  304,  the  tips  often  withering  and 
the  hyphae  extended  from  a  bud  below  as  in  A.  imperfecta,  etc. 
Sporangia  abundant,  secondary  ones  plentiful,  varying  from  short  and 
slender  to  very  long  and  slender,  or  rarely  stocky  when  short,  18-60  x 
1 05-5504;  spores  emptying  and  behaving  as  typical  in  Achlya,  10.54 
thick.  Oogonia  not  abundant,  borne  laterally  from  the  main  hyphae,  their 
stalks  of  moderate  length,  varying  from  about  as  long  to  twice  as  long 
as  the  diameter  of  the  oogonia,  or  not  rarely  even  longer;  oogonia  spher¬ 
ical  or  rarely  oval,  51-1 184  thick,  most  about  704,  the  walls  yellowish, 
not  thick,  often  strongly  pitted,  the  pits  varying  much  in  number  and 
about  5.54  wide.  Eggs  3-30  or  more,  usually  4-10,  with  a  diameter 
of  22-294,  most  about  254,  not  filling  the  oogonium  as  a  rule;  rarely 
maturing  and  of  obscure  structure,  apparently  about  like  those  of  .4. 
apiculata  when  in  normal  condition,  but  nearly  always  degenerating  im¬ 
mediately  and  becoming  irregularly  filled  with  large  oil  drops.  Anther- 
idial  branches  androgynous  or  less  often  diclinous,  usually  simple,  arising 
near  the  oogonia  from  the  main  hyphae  or  often  from  theoogonial  stalks, 
usually  one  or  two,  rarely  more,  for  each  oogonium;  antheridia  on  all 
oogonia,  cylindrical  or  long-tuberous,  usually  touching  the  oogonia  by 
foot-like  projections,  at  times  applied  by  the  entire  side;  antheridial 
tubes  obvious.  Gemmae  not  peculiar,  long,  often  in  rows  by  the  ab- 
striction  of  the  longer  threads,  frequently  with  prongs,  emptying  as  spor¬ 
angia  under  suitable  conditions. 

Found  four  times  in  Arboretum  branch  (No.  5  of  July  2,  1917, 
No.  7  of  June  29,  No.  2  of  July  24,  1920,  and  April  18,  1921). 

The  number  of  pits  may  vary  remarkably  in  the  same  culture  and 
even  on  the  same  hypha.  In  culture  No.  2  of  July  24,  1920,  on  a  termite 
some  of  the  oogonia  in  one  section  of  the  culture  were  without  any 
visible  pits  except  where  the  antheridia  touched ;  while  in  the  remainder 
of  the  culture  oogonia  with  few  to  many  pits  were  found,  both  occurring 
often  on  the  same  hypha. 

Another  peculiarity  is  the  strong  tendency  of  the  oogonial  stalk 
to  flare  beneath  the  oogonium  so  as  to  be  attached  by  a  broad  disc,  and 
this  is  often  so  exaggerated  as  to  throw  the  separation  wall  a  third  of 
the  way  up  the  oogonium. 

Achlya  americana  var.  cambrica  (see  p.  139)  is  superficially  somewhat 
like  this  but  is  easily  distinguished  by  the  smaller  and  eccentric  eggs, 
which  much  more  nearly  fill  the  smaller  oogonia,  and  by  the  origin  of 
the  antheridia  in  greater  part  from  the  main  hyphae.  The  subcentric  eggs 
place  our  plant  near  A.  polyandra  Hildebrand,  as  understood  by  Humph¬ 
rey  and  Pieters,  from  which  it  is  separated  by  the  less  numerous 
and  much  less  branched  antheridial  stalks  which  spring  both  from  the 


132 


THE  SAPROLEGNIACEAE 


main  hyphae  and  from  the  oogonial  stalks,  and  by  the  presence  of  pits 
in  the  oogonial  wall.  Hildebrand’s  original  form  is  described  as  having 
the  antheridial  branches  coming  from  the  oogonial  stalks,  and  in  this 
and  the  unpitted  walls  differs  from  A.  deBaryana.  DeBary’s  A.  gracilipes 
is  certainly  a  very  different  looking  plant  from  the  present  species, 
and  may  be  quite  distinct  from  A.  polyandra  Hildebrand. 

Possibly  representing  a  peculiar  form  of  the  present  species  is  a 
slide  prepared  by  us  in  the  fall  of  1903,  before  we  were  much  interested 
in  this  group.  The  pitted  oogonia  and  the  antheridia  are  borne  in  about 
the  same  way,  but  the  plant  seems  so  abnormal  that  we  are  not  at  all  sure 
what  it  is.  The  walls  of  the  hyphae,  the  stalks,  the  oogonia  and  even  the 
antheridia  are  mostly  very  thick  and  in  places  so  thick  as  almost  to  close 
the  lumen,  reaching  a  thickness  in  places  of  7.5^;  the  eggs  are  all  going  to 
pieces,  but  their  walls  show  them  to  be  mostly  22-2 4-j.  thick,  a  few  up  to 
30;x.  (The  plant  is  not  Aplanes  androgynous  or  A.  Treleaseanus ,  which 
have  thicker  walls  than  other  species).  The  stalks  flare  greatly  at  the  top 
and  the  wall  separating  the  oogonium  is  often  so  far  up  as  to  cut  off  a 
lower  section  of  the  oogonium,  thus  including  it  in  the  stalk.  Such  queer 
structures  can  only  be  abnormal,  and  careful  examination  of  the  oogonial 
contents  show  amongst  the  varied  detritus  certain  minute,  spherical  bodies 
of  constant  structure  and  appearance.  They  may  be  and  probably 
are  the  parasite  causing  the  trouble.  They  are  not  at  all  like  any  of  the 
chytridiacean  parasites  of  the  family.  May  they  not  be  the  amoeboid 
parasite  Vampyrellidium  vagans  Zopf,  which  has  been  insufficiently 
investigated?  (Schenck’s  Handb.  4:  540  and  565.  See  reference  to 
this  by  Fischer  ’92,  p.  325). 

18.  Achlya  oblongata  deBary.  Bot.  Zeit.  46:  646,  pi.  10,  figs.  7-9.  1888. 

Plates  46  and  47 

Mycelium  rather  stout  and  vigorous;  sporangia  subcylindric  to 
fusiform,  pointed;  dictiosporangia  not  rare;  spores  small,  about  9;jl  in 
diameter.  Gemmae  oval  like  the  eggs  or  often  linear  by  the  division 
of  the  main  hyphae.  Oogonia  very  large,  typically  oval  to  pyriform, 
rarely  nearly  spherical,  40-15010.  in  diameter  the  short  way,  borne  usually 
on  moderately  long  lateral  branches,  at  times  terminal  on  main  branches, 
rarely  intercalary;  wall  thin,  hyaline,  without  pits.  Eggs  1-28  or  30, 
rather  small,  20-30-0.,  most  about  2710.  in  diameter,  subcentric,  with  a 
lunate  (in  section)  sheath  of  oil  droplets  nearly  surrounding  the  proto¬ 
plasm;  usually  arranged  loosely  in  the  oogonium  and  not  Ailing  it,  at 
Arst  very  dark,  rarely  maturing.  Antheridial  branches  delicate  and 
slender,  always  diclinous  and  not  traceable  to  threads  bearing  oogonia; 
antheridia  on  every  oogonium,  usually  numerous,  small  and  tuberous, 
no  fertilizing  tubes  seen. 


PLATE  45 


PLATE  45 
Achlya  conspicua 

Fig.  I.-Oogonia  with  antheridia.  X  247. 

Fig.  2.  Sporangia  with  spore  cluster  at  tip.  X  167. 

Fig.  3.  Fiabit  of  oogonia,  antheridia  and  sporangia.  X  60. 

Fig.  4.  Gemmae;  also  showing  an  atrophied  growing  point  (a)  renewed  from  below. 
Fig.  5.  Oogonium  with  diclinous  antheridia.  X  247. 

Fig.  6.  Oogonium  with  conspicuous  pits.  X  247. 

Fig.  7.  Oogonium  with  eggs  undergoing  degenerative  changes.  X  447. 

Fig.  8.  Oogonium  with  both  diclinous  and  androgynous  antheridia.  X  447. 

Fig.  9.  Oogonia  showing  a  varying  number  of  pits.  X  247. 

Fig.  10.  Gemma  with  several  papillae,  through  the  longest  of  which  it  has  emptied. 


X  60. 


X  167. 


PLATE  45 


ACHLYA  CONSPICUA 


PLATE  46 


ACHLYA  CONSPICTA  [ABOVE]. 
ACHLYA  OBLONGATA  [BELOW].  X  6. 


PLATE  47 


PLATE  47 
Achlya  oblongata 

Figs.  I  and  2.  Sporangia  with  curled  tips.  X  247. 

Fig.  3.  Aplanosporangium,  with  the  tip  atrophied,  the  spores  sprouting  in  the  sporangium. 
X  247. 

Fig.  4.  A  typical  sporangium.  X  100. 

Fig.  5.  An  almost  spherical  oogonium.  X  447. 

Fig.  6.  Egg  showing  structure.  X  720. 

Fig.  7.  Sporangium  with  the  spores  forming.  X  247. 

Figs.  8,  9  and  10.  Typical  oblong  oogonia.  7  and  9  X  247;  8  X  447. 

Fig.  11.  Showing  an  aplanosporangium  and  a  typical  sporangium  on  the  same  hypha. 
X  100. 


PLATE  47 


ACHLYA  OBLONGATA 


ACHLYA 


133 


Obtained  first  from  dead  sunfish  fingerlings  from  U.  S.  Fish  Hatchery 
at  Bullockville,  Georgia,  November  13,  1916,  and  from  this  collection 
the  plate  was  made.  Found  also  at  Chapel  Hill  in  several  collections 
from  Meeting  of  the  Waters,  February  16,  1921. 

Distribution:  North  Carolina,  Georgia,  Louisiana,  Massachusetts. 
For  other  illustration  see  Humphrey  (’92),  pi.  19,  figs.  87-89. 

This  is  an  easily  distinguished  species,  the  elongated  oogonia  and 
strictly  diclinous  antheridia  on  every  oogonium  defining  it  well.  Humph¬ 
rey  also  gives  the  average  size  of  the  eggs  as  274  in  his  form,  and  says 
they  are  centric,  as  does  also  deBary.  The  structure  is,  however,  not 
truly  centric,  but  with  a  lunate  sheath  of  small  droplets  extending  most 
of  the  way  around  the  protoplasm  (pi.  47,  fig.  6).  It  is  possible  that 
in  some  eggs  the  protoplasm  may  be  quite  surrounded  by  fat  drops. 

19.  Achlya  oblongata  var.  globosa  Humphrey.  Trans.  Amer.  Phil. 

Soc.  17:  122,  pi.  19,  figs.  90-91.  1892  [1893]. 

We  have  not  found  this  variety.  It  was  obtained  by  Humphrey  from 
Pennsylvania  and  Alabama.  He  defines  it  as  like  the  type  except  that  the 
oogonial  branches  are  very  short;  the  oogonia  globular;  the  eggs  reaching 
25  in  number,  averaging  10-15.  The  oogonia  are  commonly  larger  than  in 
the  type  and  the  space  unoccupied  by  the  eggs  is  much  more  marked. 
Very  little  difference  appears  in  the  descriptions  of  this  and  A.  Klebsiana, 
except  that  it  is  implied  that  the  eggs  are  “centric”.  This  is  an  impor¬ 
tant  point,  and  if  so  will  put  it  in  a  different  group  from  A.  Klebsiana. 

20.  Achlya  glomerata  Coker.  Mycologia  4:  325,  pi.  79.  1912. 

Plate  48* 

The  following  is  copied,  with  few  changes,  from  the  original  descrip¬ 
tion: 

Hyphae  rather  stout,  branched,  not  long.  About  40-454  in  diam¬ 
eter  at  base  and  tapering  to  slender  tips  about  124  in  diameter.  At  ma¬ 
turity  the  main  hyphae  strongly  incline  to  segment  into  elongated 
sections  with  dense  protoplasm,  but  the  slender  apical  section  is  apt  to 
remain  almost  empty  (fig.  1).  Sporangia  almost  cylindrical,  inclined  to 
be  somewhat  irregular  and  often  opening  by  a  bent  papilla  (fig.  2). 
Oogonia  abundant,  approximately  spherical,  without  pits;  completely 
covered  with  short,  blunt,  irregular  warts  29-444  thick,  with  the  warts 
most  about  334  thick  (fig.  3).  Oogonia  borne  on  the  tips  of  very  slender 
and  delicate,  but  contorted  lateral  branches  that  are  either  simple,  in 
which  case  there  is  but  one  oogonium  (fig.  3),  or  more  or  less  intricately 
branched,  in  which  case  there  are  a  number  of  oogonia  borne  on  the 
tips  of  the  group  of  branches  (figs.  4,  5,  and  6).  Eggs  single  or  very 


*This  plate  is  a  reproduction,  with  slight  changes,  of  the  plate  in  Mycologia. 


134 


THE  SAPROLEGNIACEAE 


rarely  two  in  an  oogonium,  eccentric,  their  diameter  15-23^,  averaging 
about  20[jl.  Antheridia  absent  from  a  good  many  oogonia,  when  present 
club-shaped;  borne  on  the  tips  of  branches  from  the  same  glomerulus 
and  one  or  several  on  an  oogonium  (fig.  5). 

This  species  has  been  observed  several  times  from  two  stations 
at  Chapel  Hill,  North  Carolina.  The  drawings  are  made  from  material 
taken  from  a  cool  spring  in  dense  woods  (Lone  Pine  spring)  on  April  30, 
1912,  and  from  the  springy  marsh  at  the  foot  of  Lone  Pine  hill  on  Feb¬ 
ruary  29,  1912.  Pure  cultures  have  been  continued  for  six  months  or  more. 

This  species  does  not  closely  approach  any  other,  but  it  seems  to 
be  nearest  the  members  of  the  Racemosa  group.  The  shape  of  the  an¬ 
theridia  is  like  those  of  A.  racemosa  and  its  relatives,  and  there  is  con¬ 
siderable  resemblance  to  the  spiny  oogonia  of  A.  colorata  and  A.  radiosa. 
There  is  also  some  hint  of  the  habit  of  A.  glomerata  in  the  occasional  branched 
oogonial  threads  of  A.  radiosa.  In  all  the  members  of  the  Racemosa  group 
the  antheridial  branches,  when  present,  originate  just  below  the  oogonium. 
In  A.  glomerata  they  do  not  thus  originate.  This  distinction  with  the  usually 
bent  and  twisted  branching  habit  of  the  oogonial  hyphae  separates 
the  species  sharply  from  any  of  the  Racemosa  group.  As  already  men¬ 
tioned,  the  oogonia  are  sometimes  borne  singly  on  the  ends  of  simple 
branches,  especially  near  the  tips  of  the  main  hyphae,  but  in  such  cases 
these  branches  are  much  more  delicate  and  longer  in  proportion  to  the 
oogonia  than  is  generally  the  case  in  any  member  of  the  Racemosa  group. 
Achlya  spinosa  has  but  one  or  two  eggs  (rarely  three)  in  an  oogonium 
and  may  be  the  closest  relative  of  A.  glomerata.  It  differs  easily  in  the 
barrel-shaped  oogonia  with  an  apical  papilla,  in  the  antheridia  arising 
just  beneath  the  oogonia,  and  in  the  absence  of  clustered  groups  of 
oogonia. 

The  fruiting  branches  are  so  abundant  and  many  of  them  are  so 
elongated  and  extensively  branched  that  the  cultures  take  on  a  whitish, 
cottony  appearance  except  near  the  periphery,  which  is  usually  without 
branches.  In  extreme  cases  this  effect  is  so  pronounced  that  the  culture 
may  be  compared  in  appearance  to  a  rug  with  a  fringe.  This  reminds 
us  of  the  “woolly  snow-white  turf”  produced  by  deBary’s  Achlya  spinosa 
(’88,  p.  647),  which  species,  while  not  in  the  close  family  circle  of  the 
Racemosa  group,  shows  its  relation  to  them  by  its  spiny  oogonia  with 
generally  one  egg,  and  by  the  origin  and  shape  of  the  antheridia. 

So  far  as  the  sexual  organs  are  concerned,  there  is  a  remarkably 
close  resemblance  between  Achlya  glomerata  and  Saprolegnia  aster ophora 
deBary.  As  in  most  species  of  Achlya ,  the  spores  sometimes  remain 
in  the  sporangium  and  sprout  there  (Coker,  To,  p.  381). 

Pure  cultures  from  No.  10  of  April  30,  1912: 


PLATE  48 


PLATE  48 

(Taken  with  slight  changes  from  PI.  79  of  Mycologia  4.  1912.) 

Achlya  glomerata 

Fig.  I.  Part  of  filament  from  an  old  culture,  showing  segmentation  into  gemmae.  Part  of 
one  long  cell  is  omitted.  The  contorted  tip  cell  is  almost  empty.  X  185. 
Fig.  2.  A  group  of  sporangia  in  different  stages.  X  125. 

Fig.  3.  An  oogonium  containing  a  ripe  egg.  X  335. 

Fig.  4.  A  branched  oogonial  filament  with  two  oogonia.  X  335- 

Fig.  5.  A  more  complex  group  of  oogonia,  not  all  shown.  One  is  intercalary.  X  335- 
Fig.  6.  A  characteristic  group  of  oogonia  with  antheridia.  X  335. 

Fig.  7.  A  sporangium  in  which  the  spores  became  encysted  and  sprouted  in  position  X  335- 


PLATE  4S 


ACHLYA  GLOMERATA. 


ACHLYA 


135 


In  maltose  5  %  peptone  .01  %.  Oogonia  in  fairly  large  number,  and  reaching  full  size 
with  tubercles,  but  no  antheridia  and  no  eggs  formed,  contents  going  to  pieces. 

On  corn  meal  agar.  Growth  limited  and  purely  vegetative.  The  threads  became  segment¬ 
ed  up  into  long  sections,  with  dense  protoplasm,  as  usual  in  the  species. 

In  equal  parts  of  maltose-peptone  and  pea  broth.  Growth  good,  about  1  inch  in  diameter, 
dense  and  thick.  A  good  many  oogonia,  and  with  normal  eggs  in  most.  Antheridia 
on  every  oogonium,  apparently — certainly  on  nearly  all. 

On  corn  meal  egg  yolk  agar.  Growth  slow,  but  extending  over  about  a  2-inch  circle,  many 
hyphae  standing  up  into  air  Vs  inch,  but  not  dense.  A  considerable  number  of  oogonia 
with  good  eggs.  Some  had  antheridia. 

In  the  following  cultures  equal  parts  of  a  2%  solution  of  the  salts 
and  of  maltose-peptone  solution  (one  part  of  5%  maltose+one  part 
of  .01%  peptone)  were  used: 

In  Ca(N03)2  +  maltose-peptone  solution.  Strong,  healthy  vegetative  growth,  about  1 

nch  in  diameter.  No  reproduction  of  any  kind. 

In  KNO3  +  maltose-peptone  solution.  Growth  as  in  preceding  experiment.  No  re¬ 
production. 

In  Ca3(PO,h  +  maltose-peptone  solution.  Growth  as  in  two  preceding  experiments, 
except  somewhat  more  delicate.  No  reproduction. 

In  KH2PO4  +  maltose-peptone  solution.  Most  extensive  growth  of  any  in  this  series.  No 
reproduction. 

In  NaH2P04  +  maltose-peptone  solution.  Growth  short,  contorted,  and  protoplasm  seg¬ 
regated  into  spots  in  larger  hyphae.  No  reproduction. 

In  K2SO4  +  maltose-peptone  solution.  Growth  delicate,  about  1  inch  in  diameter.  No 
reproduction. 

Experiments  to  test  the  best  method  of  preserving  live  cultures: 

Culture  on  corn  meal  agar  put  in  vial  of  water,  which  was  closed  with  a  plug  of  cotton  and 
put  in  dark  place  in  May,  1913.  Test  for  life  was  made  in  December,  1913,  and  it  was 
found  to  be  alive  (all  old  eggs  were  dead). 

Culture  as  above  made  March  17,  1913,  was  found  to  be  dead  on  December  1,  1913. 
Culture  placed  in  aquarium  jar  with  algae  in  laboratory  on  March  7,  1913.  No  growth 
appeared  when  tested  on  September  18,  1917. 

21.  Achlya  dubia  n.  sp. 

Plate  49 

Main  threads  stout,  little  branched,  only  about  5  mm.  long  on  a 
termite,  up  to  about  50  or  6o;j.  thick,  tapering  gradually,  the  rather 
blunt  tips  clear  and  refractive  while  growing.  Sporangia  abundant, 
terminating  the  main  hyphae,  long,  only  slightly  thicker  than  the  threads, 
tapering  a  little  towards  the  tip,  increased  sparingly  by  growth  from 
below  as  in  Achlya;  when  mature  discharging  the  spores  as  in  Achlya 
or  as  in  Thraustotheca  in  varying  proportion,  often  about  half  and  half 
on  a  termite  in  sterilized  well  water,  not  rarely  behaving  as  in  Dicty- 
uchus.  Spores  normally  about  1 1.5^  thick  (but  often  much  larger  masses 
of  protoplasm  are  found  among  them),  encysting  on  emerging  from  the 
sporangium  and  escaping  for  a  swimming  stage  as  in  Achlya.  Gemmae 
abundant,  formed  by  partitions  in  the  threads  behind  the  sporangia, 


THE  SAPROLEGNTACEAE 


136 

hence  subcylindrical,  often  bending  and  partly  separating  at  the  joints, 
soon  forming  spores  which  escape  as  in  Adilya  by  a  papilla  of  variable 
length.  Oogonia  borne  on  short  lateral  stalks  from  the  main  hyphae, 
rarely  terminal  on  the  latter,  smooth,  spherical,  very  regular  in  size, 
50-6510.,  most  about  604,  the  rare  terminal  ones  up  to  904  thick;  wall 
rather  thin,  not  pitted  except  under  the  antheridia,  distinctly  yellow- 
brown.  Eggs  few,  2-5,  in  large  oogonia  about  6  or  8,  in  diameter  24- 
33ix,  most  about  28-304,  when  nearly  mature  with  several  oil  drops  on 
one  side,  then  usually  with  a  single,  lateral,  conspicuous  drop  at  full 
maturity  (but  mature  oogonia  not  rarely  still  contain  several  or  a  good 
many  oil  drops).  Antheridia  on  all  oogonia,  usually  cylindrical  and 
partly  wrapped  about  the  oogonia,  diclinous,  borne  on  sparingly  branched 
threads  of  moderate  length  from  main  hyphae  or  on  long  threads  which 
terminate  more  slender  hyphae;  antheridial  tubes  obvious  and  visible 
for  a  long  time. 

This  remarkable  plant  has  appeared  but  twice.  It  was  found  in 
a  collection  from  a  branch  (Meeting  of  the  Waters,  No.  5,  of  February  16, 
1921)  where  the  water  is  somewhat  contaminated  by  a  sewer  which  enters 
about  a  half  mile  farther  up.  Pure  cultures  were  made  and  are  being 
continued.  Leptomitus  and  Adilya  oblongata  were  found  at  the  same  place. 
It  was  found  again  near  Hartsville,  S.  C.,  August  30,  1922.  In  the  behavior 
of  the  sporangia  and  spores  the  species  is  exactly  intermediate  between 
Adilya  and  Thraustotheca,  or  rather  it  combines  in  this  respect  the  characters 
of  both.  The  eggs  are,  however,  more  like  the  latter  genus,  the  eggs 
having  several  conspicuous  lateral  droplets  up  to  a  late  stage  as  in  T.  davata 
and  differing  thus  from  the  eccentric-egged  Achlyas.  Our  figures  do  not 
show  extreme  condition  of  the  late  stage,  in  which  the  protoplasm  draws 
away  from  the  droplet  as  much  as  in  A .  Orion.  The  antheridial  branches  also 
remind  one  of  those  of  T.  davata  and,  as  in  it,  are  always  diclinous.  The 
distinctly  brown  oogonial  wall  is  also  different  from  any  Achlya  with 
eccentric  eggs.  In  such  ways  this  seems  nearer  Thraustotheca  than 
Achlya ,  but  for  various  reasons  we  prefer  to  put  the  species  in  Achlya 
at  present.  The  strongest  reason  is  that  as  our  cultures  have  gone  on 
the  Thraustotheca-Yike  sporangia  have  grown  fewer  in  proportion. 

The  majority  of  the  Thraustotheca-Yike  sporangia  have  the  peculiar 
habit  of  cutting  off  a  considerable  area  at  the  tip  which  does  not  form 
spores  but  contains  much  less  dense  protoplasm  which  usually  goes  to 
pieces  but  may  become  condensed  into  a  ball.  Other  parts  of  the  spor¬ 
angium,  particularly  the  basal  part,  may  also  fail  to  form  spores,  the 
protoplasm  remaining  undivided  or  imperfectly  segmented  into  large 
masses.  Even  when  the  spores  are  discharged  at  the  tips  larger  masses 
may  be  mixed  with  the  normal  spores,  as  is  not  rare  in  other  water  molds. 
(See  Achlya  imperfecta.)  The  sporangial  wall  may  begin  its  disorgani¬ 
zation  at  any  point,  but  this  usually  shows  first  on  one  side  near  the  cen- 


PLATE  49 


PLATE  49 
Achlya  dubia 

Fig.  I.  A  row  of  gemmae,  most  of  which  have  already  formed  and  discharged  spores.  X 
167. 

Fig.  2.  Two  threads  both  bearing  sporangia,  one  with  an  oogonium,  the  other  with  anther- 
idial  branches.  X  167. 

Fig.  3.  A  sporangium  beginning  to  disorganize  on  one  side;  below  it  a  younger  sporangium 
cut  from  the  main  thread  and  with  spores  emptied  as  in  Achlya.  X  167. 

Fig.  4.  A  sporangium  (with  tip  cut  off  as  in  most  cases),  the  spores  sprouting  through  the 
wall.  Through  these  tubes  the  spores  emerged  as  in  Dictyuchus.  X  167. 

Fig.  5.  A  sporangium  well  advanced  toward  dissolution.  X  167. 

Fig.  6.  A  sporangium  still  further  disorganized  attached  to  a  younger  sporangiumwhich 
has  discharged  spores  as  in  Achlya.  X  167. 

Fig.  7.  A  sporangium  with  the  walls  all  gone,  the  tip  showing  two  undeveloped  cells.  X  167. 

Fig.  8.  A  disorganizing  sporangium  with  two  discarded  and  disorganizing  cells  at  both 
tip  and  base;  below  a  segment  is  developing  into  a  sporangium.  X  167. 

Fig.  9.  A  group  of  liberated  spores,  some  with  abnormal  size  and  shape.  X  167. 

Fig.  10.  A  sporangium  in  which  disorganization  of  the  wall  began  near  the  tip.  X  167. 

Fig.  11.  A  sporangium  discharged  as  in  Achlya,  with  some  of  the  spores  escaped  from  their 

cysts.  X  167. 

Fig.  12.  An  oogonium  with  fully  mature  (rather  old)  eggs,  two  with  many  oil  drops,  one 
(the  more  common  case)  with  only  a  single  drop  (antheridium  too  far  dis¬ 
organized  to  be  shown).  X  447. 

Fig.  13.  A  young  oogonium  with  a  typical  antheridial  branch.  X  167. 

Fig.  14.  A  dictiosporangium  with  an  empty  sporangium  below.  X  167. 

Fig.  15.  An  oogonium  with  maturing  eggs,  the  antheridium  still  visible.  X  447. 

Fig.  16.  Two  Achlya-Uke  sporangia,  the  lower  emptying  from  one  side.  X  60. 

Fig.  17.  Spores  in  the  swimming  stage  (cilia  not  shown).  X  417. 

Fig.  18.  A  hypha  with  racemosely  arranged  oogonia  (typical)  and  a  large  terminal  one. 

Most  of  the  oogonia  were  halted  in  their  development  and  did  not  mature. 
Antheridia  are  attached  only  to  those  which  are  maturing  normally.  X  108. 


PLATE  49 


ACHLYA  DUBIA 


ACHLYA 


137 


ter.  As  the  spores  swell  and  become  more  separated  and  as  the  dis¬ 
organization  continues  the  curving  may  continue  until  a  complete  circle 
is  formed  (fig.  7).  If  the  rupture  starts  near  the  tip  the  spores  may 
spread  out  like  a  shaving  brush  (fig.  10).  If  the  spores  are  not  discharged 
the  disorganization  of  the  wall  is  not  long  deferred,  but  begins  in  a  few 
hours,  just  as  in  Thraustotheca.  In  case  dictiosporangia  are  formed 
the  emptying  tubes  are  often  quite  long,  so  long  in  fact  that  one  often 
thinks  the  tubes  are  going  to  elongate  into  threads  as  in  Aplanes,  only 
to  find  that  the  spores  emerge  through  them  a  little  later  (figs.  4  and  14). 


22.  Achlya  sp.?  Form  without  oogonia. 

Plate  50 

Weston  (’17)  found  in  Massachusetts  a  species  of  A  chlya  which  remained 
sexually  sterile  during  the  entire  period  of  culture  on  different  media 
(over  two  years).  During  last  August  we  also  found  a  sterile  Achlya 
(No.  1  of  August  13,  1921)  in  trash  and  leaves  collected  from  a  branch  in 
Strowd’s  low-ground  pasture,  which  appears  to  be  the  same  thing. 
(Compare  also  Tiesenhausen ’s  sterile  species  mentioned  on  p.  148). 
We  have  cultivated  this  plant  continually  since  (about  7  months,  at  time 
of  writing)  and  in  many  different  ways  and  on  many  media,  but  only  spor¬ 
angia  and  gemmae  have  appeared.  The  latter,  while  not  very  peculiar,  are 
often  in  chains  and  are  of  a  short,  plump  type,  often  spherical,  a  form  that 
excludes  many  species  with  much  elongated  gemmae.  The  size  and  habit 
of  growth  of  the  plant  and  the  form  of  the  sporangia  are  about  that  of  a 
typical  Achlya,  as  A.  intermedia.  On  a  termite  ant  the  threads  grow 
about  0.5  cm.  long  and  are  about  30-70^  thick  below  to  20-30’j.  thick  near 
the  tips.  The  sporangia  are  plentiful  and  proliferate  so  as  to  form  clusters 
of  several.  The  gemmae  are  spherical,  ovate  or  oblong,  sometimes  in 
chains  of  as  many  as  six;  their  diameter  runs  up  to  as  much  as  iio;j.  for 
the  spherica’  ones  (figs.  1-4).  Results  of  experiments  with  chemicals 
will  not  be  given  in  detail,  but  culture  media  used  are  given  below  to 
show  the  reluctance  of  the  plant  to  form  sexual  organs: 

12  cc.  .05%  solution  of  haemaglobin  plus  the  following  salts: 

(1)  2  cc.  2%  Ca3  (P04)2 

(2)  2  cc.  2%  Ca  (NOA 

(3)  2  cc.  2%  K2  S04 

(4)  2  cc.  2%  Na2  HPO4 

(5)  2  cc.  2%  KH2  PO4 

25  cc.  of  a  solution  of  levulose  ^3  +  leucine  3^3.  The  solution  being  replaced  by  water 
in  60  hours.  Five  cultures  in  room  temperature  21-26°  C.  Five  cultures  in  ice  box  temp¬ 
erature  10—120  C. 


THE  SAPROLEGNIACEAE 


138 


25  cc.  levulose  ^  +  leucine  plus  the  following  salts: 

(1)  10  drops  2%  Mg  S04 

(2)  10  drops  2%  KNO3 
10  drop^  2%  NaCl 
10  drops  2%  Ca3  (POO2 
10  drops  2%  Ca  (N03)2 


'3) 

(4) 

(5) 

(6) 

(7) 

(8) 


10  drops  2%  Na2  HP04 


10  drops  2%  KH2  PO4 
10  drops  2%  K2  SO4 

Cochineal  bugs  were  inoculated  with  the  fungus  and  after  ten  days  growth  many  of  the 
threads  had  become  green  in  color.  These  green  threads  were  otherwise  perfectly  normal 
and  in  a  healthy  condition.  The  gemmae  were  almost  uniformly  red. 

Experiments  to  determine  the  resistance  of  the  gemmae  to  extreme  temperatures: 

(1)  Resistance  to  cold.  A  culture  with  a  number  of  resistant  spores  was  placed  on  a  block 
of  ice  in  the  ice  box  and  allowed  to  remain  there  over  night.  The  following  morning  the 
resistant  spores  were  uninjured. 

(2)  Resistance  to  heat.  The  same  culture  used  in  No.  1  was  transferred  to  a  petri  dish 
of  hot  agar  which  had  just  been  melted  in  boiling  water.  The  inoculated  agar  plate  was 
left  out  in  room  temperature  and  after  two  days  growth  had  taken  place  to  a  length  of  1  cm. 


EUROPEAN  SPECIES  NOT  YET  FOUND  IN  AMERICA 

Achlya  spinosa  deBary.  Beitr.  z.  Morph.  11.  Phys.  der  Pilze4:  54,  pi. 

4,  figs.  13-18.  1881. 

The  following  is  translated  from  the  fuller  description  of  1888  (p. 

64-)- 

“Main  threads  with  many  long  interwoven  side  branches  which 
produce  a  woolly,  snow-white  turf  which,  if  well  nourished,  may  reach 
a  height  of  2-3  cm.  Reproductive  organs  sparingly  produced.  Zoo¬ 
sporangia  small,  and  producing  few  spores;  often  lacking.  Oogonia 
terminal,  never  intercalary  [but  see  below],  mostly  barrel-shaped,  densely 
set  with  numerous,  broadly  conic,  pointed  or  blunt  projections,  only 
the  upper  and  lower  ends  bare,  the  upper  end  with  a  conical  point  which 
may  be  extended  into  a  long  beak.  Eggs  1-2,  rarely  3,  in  an  oogonium; 
of  very  various  sizes,  always  about  filling  the  oogonium;  round  or  oval 
when  ripe  with  a  large  central  fat  globule  and  a  circular  or  interrupted 
row  of  peripheral  globules  [Korner];  without  an  obvious  nuclear  spot. 
Antheridia  about  as  often  absent  as  present;  in  the  latter  case  always 
(?)  only  one  on  an  oogonium;  they  are  cylindrical-club-shaped  and  lay 
one  side  on  the  oogonium,  their  short  stalks  springing  from  just  below  the 
oogonial  wall,  rarely  of  diclinous  origin. 

“Found  once  in  the  Titisee  [lake]  in  the  Black  Forest,  June,  1880.” 

The  above  description  does  not  agree  with  the  original  one  in  saying 
that  the  oogonia  are  never  intercalary,  as  the  figures  show  several  that  are. 
See  remarks  under  A.  glomerata. 


PLATE  50 


PLATE  50 

Achlya  sp.?  Form  without  oogonia. 

Figs.  I,  2,  3.  Various  forms  of  gemmae.  Figs.  1,  3  X  108;  2  X  167. 

Fig.  4.  A  chain  of  gemmae,  the  contents  of  which  have  formed  spores.  X  167. 

Achlya  apiculata  var.  prolifica 
Fig.  5.  Sprouting  egg.  X  100. 

ISOACHLYA  MONILIFERA 

Fig.  6.  Sporangia  showing  internal  proliferation.  X  167. 

Fig.  7.  Internal  proliferation  as  in  Saprolegnia  and  cymose  proliferation  as  Achyia. 
X  167 

Fig.  8.  A  chain  of  oogonia  in  a  sporangium.  X  if>7. 

Fig.  9.  Irregular  oogonia  in  a  chain.  X  167. 

Fig.  10.  Moniliform  sporangium.  X  167. 

Fig.  11.  Sporangium  renewed  by  cymose  branching.  X  167. 

Fig.  12.  Spore  stained  to  show  cilia.  X  720. 

Aphanomyces  scaber 

Fig.  13,  14  Sporangia  and  encysted  spores.  X  720. 

Fig.  15,  16.  Oogonia  with  ripe  eggs.  X  720. 

Aphanomyces  laevis. 

Fig.  17.  The  fungus  shown  growing  parasitically  on  a  chain  of  desmids.  X  447. 


PLATE  50 


ACHLYA  SP.  (  ?).  FIGS.  1-4. 

ACHLYA  APICULATA  VAR.  PROLIFICA.  FIG.  5. 
ISOACHLYA  MONILIFERA.  FIGS.  6-1  o 
APHANOMYCES  SCABER.  FIGS.  13-16. 
APHANOMYCES  LAEVIS,  PARASITIC  FORM.  FIG  17 


ACHLYA 


139 

Achlya  radiosa  Maurizio.  Mitt.  d.  Deutsch.  Fischerei-Vereins  7,  Heft  1 : 

57,  figs.  18  and  19.  1899. 

A.  decorata  Petersen.  Bot.  Tidsskr.  29:  386.  1909.  Also  in  Ann. 

Myc.  8:  522,  figs.  3a  and  3e.  1910. 

A.  asterophora  Minden.  Ivrypt.  FI.  Mark  B.  5:  549,  fig.  2c  on  p. 

520.  1912. 

This  species,  described  three  t’mes  in  rather  recent  years  in  Europe, 
has  not  been  found  in  America.  The  prior  description  by  Maurizio 
may  be  condensed  as  follows: 

Hyphae  dense,  about  1-1.5  cm.  long,  14.5-494  thick,  thickened 
in  places.  Sporangia  typical  of  the  genus,  cylindrical,  sympodially  ar¬ 
ranged,  often  bearing  an  oogonial  branch  below  them.  Zoospores  as 
usual.  Oogonia  typically  racemosely  borne,  or  also  on  main  or  sec¬ 
ondary  hyphae;  spherical,  with  thorny,  pointed  warts  over  whole  sur¬ 
face;  wall  yellowish,  diameter  without  spines  31.5-464,  with  them  40- 
54.54.  Spines  7-124  long,  9.5-124  thick  at  base.  Eggs  one,  rarely 
two,  or  more  rarely  three  in  somewhat  elongated  oogonia,  Piling  the 
oogonium.  Egg  membrane  clear  yellow;  contents  thick,  with  numerous 
large  and  small  fat-drops  [does  not  say  whether  centric  or  eccentric]; 
diameter  29-394,  mostly  34-36.54.  Antheridia  on  short  bent  stalks 
from  the  oogonial  stalk  or  the  main  hyphae;  club-shaped,  present  on 
most  of  the  oogonia.  Antheridial  tubes  nearly  always  present.  In  some 
cases  sporangia  halt  in  development  and  after  a  while  drop  off,  and 
when  brought  into  nourishing  media  sprout  to  hyphae.  Typical  gem¬ 
mae  not  present.  The  species  is  nearest  A.  stellata  deB.,  which  it  re¬ 
sembles  in  the  one-egged,  spiny  oogonia.  In  other  ways  it  is  quite 
different.  Found  on  the  eggs  of  American  brook  trout,  in  the  fish  hatch¬ 
ery  at  Munchhausen  Reg.  Bez.  Cassel. 

Not  only  the  above  description,  but  the  figures  also,  leave  no  doubt 
of  the  identity  of  this  species  with  those  of  Petersen  and  Minden.  It 
is  also  quite  possible  that  the  insufficiently  described  S.  racemosa  var. 
spinosa  Cornu  is  the  same,  but  there  seems  no  way  to  be  sure.  The 
species  is  distinguished  from  A.  colorata  by  the  oogonia  containing 
but  one  egg  as  a  rule  and  by  the  dense,  sharp  spines.  Tiesenhausen 
(’12,  p.  283)  finds  two  slightly  different  forms  of  A.  radiosa  and  gives  a 
good  figure  of  the  ripe  egg.  He  shows  it  (fig.  13)  in  section  with  oil  drops 
most  of  the  way  around  (subcentric).  For  a  good  account  of  A.  decorata 
with  figures  and  the  results  of  numerous  cultures  and  experiments,  see 
Obel  (’10,  p.  421,  figs.  1-4). 

Achlya  americana  var.  cambrica  Trow.  Ann.  Bot.  13:  135,  pis.  8-io* 
1899. 

Trow's  description  we  append  below: 

“Mycelium,  as  developed  on  house-flies,  with  main  hyphae  about 
1  cm.  long,  a  maximum  diameter  at  the  base  of  924,  and  tapering  grad- 


140 


THE  SAPROLEGNIACEAE 


ually  towards  the  apices,  where  they  rather  suddenly  narrow  to  fairly 
sharp  points. 

“Sporangia  terminal,  cylindrical,  scarcely  thicker  than  the  sup¬ 
porting  hyphae,  of  a  length  generally  varying  from  2504  to  368;x  and  of 
a  breadth  varying  from  39[x  to  724  (average  of  six  measurements — 
length  3 1 5p.,  breadth  56^);  sometimes  very  small,  producing  in  extreme 
cases  no  more  than  three  or  four  zoospores;  generally  developed  in  the 
typical  cymose  order,  the  main  axis ,  however,  frequently  septate  behind 
the  oldest  sporangium ,  each  segment  thus  formed,  of  which  there  may  be  as 
many  as  ten,  developing  a  short  branch,  the  segment  and  branch  together 
constituting  a  sporangium. 

“Spores  very  numerous,  averaging  13^  in  diameter,  generally  en¬ 
cysting  at  the  mouth  of  the  sporangium,  occasionally,  however,  in¬ 
side  it. 

“Oogonia,  on  short  unbranched  stalks,  which  are  about  as  long 
as  the  diameter  of  the  oogonium,  and  of  an  average  breadth  of  io^l;  at 
first  developed  regularly  in  racemose  order  on  the  main  hyphae;  gener¬ 
ally  terminal  and  spherical,  but  not  infrequently  intercalary  and  barrel¬ 
shaped;  of  a  diameter  3i[j.  to  85^  (average  of  twelve  measurements  6o;x), 
with  a  thick,  pitted,  yellowish  smooth  wall ;  frequently,  however,  provided 
with  blunt  spines,  which  may  exceptionally  even  reach  the  length  of  25 n, 
and  are  due  to  outgrowths  through  the  pits. 

“Antheridia,  always  present  under  natural  conditions,  few  in  num¬ 
ber,  produced  on  branched  antheridial  filaments  of  a  diameter  of  6.5^, 
which  arise  from  the  main  hyphae  side  by  side  with  the  oogonial  branches, 
or,  as  observed  in  a  very  few  cases  only,  from  the  stalk  of  the  oogonium ; 
of  very  variable  shape,  but  generally  long  and  curved,  and  closely  applied 
throughout  to  the  surface  of  the  oogonium,  or  opposite  the  pits  only  by 
means  of  outgrowths  from  the  under  surface;  sometimes  septate;  of  a 
maximum  length  of  65UL  and  maximum  breadth  of  7^.;  emitting  from 
points  in  contact  with  the  pits  one  or  more  branched  or  unbranched 
fertilization-tubes  of  a  diameter  of  qp.. 

“Oospores,  one  to  twenty  or  more,  mostly  from  three  to  eight  (aver¬ 
age  of  twelve  cases  six) ;  spherical,  with  a  smooth,  very  thick  two-layered 
wall;  eccentric,  of  a  diameter  of  23^  to  26;j.,  and  having  an  oil-globule  of 
a  diameter  of  15a;  germinating  at  once,  and  producing  a  long,  thin, 
branched  hypha,  or  one  or  more  small  sporangia,  or  passing  into  a  rest¬ 
ing  condition  and  remaining  capable  of  germination  for  at  least  four 
months.” 

A  little  further  on  (p.  137)  Trow  says: 

“The  specific  type  as  described  and  figured  by  Humphrey  has  ob¬ 
viously  rather  indistinct  pits;  the  form  I  am  familiar  with  has  pits  al¬ 
most,  if  not  quite,  as  well-defined  as  those  of  the  Ferax  group  of  species 
of  Saprolegnia.  The  American  plants,  too,  apparently  differ  from  those 
which  I  have  examined  in  the  greater  number  of  antheridial  branches 
and  antheridia  supplied  to  each  oogonium,  the  color  of  the  wall  of  the 
oogonium,  the  structure  of  the  oospore  wall,  and  the  size  of  the  oospores. 
Other  noteworthy  points  of  difference  have  been  indicated  by  italics  in 
the  description  of  the  variety.” 


ACHLYA 


141 

Trow  found  that  in  his  plant  the  antheridia  were  suppressed  when 
bits  of  mycelium  with  young  oogonia  were  cut  off  and  put  in  a  moist 
chamber. 

It  was  on  this  variety  that  Trow  did  a  good  piece  of  cytological 
work  and  came  to  the  well-founded  conclusion  that  fertilization  takes 
place.  As  to  cytology  and  fertilization  of  the  egg  his  conclusions  may 
be  briefly  summarized  as  follows:  The  vegetative  nucleus  has  a  membrane 
and  a  central  spongy  body  containing  chromatin  and  nucleolar  matter 
from  which  linin  threads  extend  to  the  membrane;  the  nuclei  divide 
in  the  hyphae  and  large  numbers  enter  the  sporangia  and  the  oogonia; 
in  the  former  no  divisions  take  place,  but  in  the  oogonia  many  at  least 
of  the  nuclei  divide  mytotically,  with  the  number  of  chromosomes  prob¬ 
ably  four  [?];  after  this  division  there  are  about  ten  times  as  many  nuclei 
as  there  will  be  eggs  and  all  now  degenerate  except  the  number  necessary 
to  supply  each  egg  with  a  single  nucleus,  which  becomes  the  egg  nucleus. 
The  antheridia  are  multinucleate  and  their  nuclei  “undergo  exactly  the 
same  changes  as  those  in  the  adjacent  oogonia.”  In  fertilization  a  tube 
containing  one  male  nucleus  touches  the  naked  egg  and  discharges  into 
it  a  nucleus  and  some  protoplasm.  The  egg  and  sperm  nuclei  then  to 
all  appearances  fuse,  though  the  process  was  not  followed  through  all 
stages.  The  ripe  egg  contains  a  single  nucleus,  and  may  germinate  at 
once  or  after  as  long  a  rest  as  four  months;  the  nucleus  divides  mytot¬ 
ically  to  produce  about  twenty  nuclei,  showing  about  eight  chromo¬ 
somes.  The  egg  now  sprouts  to  form  sporangia  or  hyphae. 

Achlya  deBaryana  Humphrey.  Proc.  Am.  Phil.  Soc.  17:  117.  1892 
[1893]. 

Achlya  polyandra  deBary.  Beit.  z.  Morph,  u.  Phys.  d.  Pilze  4: 
49,  pi.  4,  figs.  5-12.  1881. 

Not  Achlya  polyandra  Hildb.  (See  Humphrey,  ’92,  p.  118.) 

This  has  not  been  recognized  in  America,  and  we  take  the  following 
from  deBary’s  condensed  statement  of  1888  (p.  364): 

“Main  hyphae  stout,  usually  ending  in  primary  sporangia  under 
which  the  secondary  ones  appear  in  sympodial  arrangement.  Oogonia 
short-stalked,  racemosely  arranged,  seldom  intercalary  and  often  ter¬ 
minal  on  slender  hyphae;  wall  stout,  here  and  there  with  somewhat  thin¬ 
ner  places  but  not  pitted,  occasionally  with  a  few  wart-like  projections. 
Antheridial  branches  almost  always  androgynous,  much  contorted  and 
branched,  arising  from  the  same  principal  axes  which  bear  the  oogonia, 
but  never  from  the  oogonial  stalks.  Antheridia  on  the  branched  tips 
of  the  antheridial  branches  attached  by  their  sides  to  the  oogonia  and 
sending  into  them  one  or  two  fertilizing  tubes  each.  Eggs  varying  in 
number,  but  mostly  numerous,  eccentric.” 


142 


THE  SAPROLEGNIACEAE 


Fischer  uses  the  form  A.  polyandra  (Hildb.)  deB.,  and  treats  it 
in  the  sense  of  deBary,  remarking  that  Hildebrand’s  original  form  is 
an  approach  to  A.  gracilipes  deB.  and  stands  between  it  and  A.  poly¬ 
andra  deB.  From  Fischer’s  description  we  take  the  following  addi¬ 
tional  data: 

Main  threads  100-150^  thick;  sporangia,  e.g.,  45  x  280^,  often  very 
large;  oogonial  stalks  1-3  times  as  long  as  the  diameter  of  the  oogonia, 
8— 1 4;j.  thick;  oogonia  45-65^  thick;  antheridial  branches  8-14^  thick, 
1-4  for  each  oogonium;  eggs  3-10  or  more,  rarely  only  1  or  2,  diameter 
1 8-2 5 [x,  certainly  eccentric,  germinating  into  mycelium  or  a  sporangium, 
resting  period  21-37  days.  Von  Minden  (’12)  accepts  Humphrey’s 
name,  and  seems  to  take  his  description  from  Fischer.  He  describes  the 
var.  intermedia  (which  we  find  and  are  treating  as  a  species). 

DeBary  does  not  give  the  size  of  the  eggs,  but  his  figures  (1.  c.,  ’81) 
show  the  eggs  distinctly  larger  than  those  of  A.  prolifera  on  the  same 
plate,  at  the  same  magnification. 

The  species  is  apparently  nearest  A.  americana.  For  a  comparison 
with  this  and  others  of  the  same  group  see  under  the  genus  and  under 
A.  flagellata.  For  other  illustrations  see  Ward  (’83),  pi.  22,  figs.  1-14; 
Zopf  (’90),  fig.  45;  Minden  (’12),  fig.  2e  on  p.  520;  Horn  (’04),  figs.  1-2 1. 

Trow  has  fully  proved  sexuality  in  this  species  (’04).  The  phe¬ 
nomena  are  about  the  same  as  shown  in  his  earlier  paper  on  Saprolegnia 
diclina  and  S.  mixta  except  that  he  claims  (probably  incorrectly)  that 
after  the  first  division  of  nuclei  in  the  oogonium  a  second  occurs  in  at 
least  some  of  the  daughter  nuclei  in  which  the  chromosome  number  is 
reduced,  apparently,  from  eight  to  four.  All  nuclei  now  degenerate 
except  one  for  each  egg.  The  egg  nucleus  shows  a  centrosome  with 
astral  rays  and  so  does  the  sperm  nucleus  soon  after  it  enters  the  egg. 
These  bodies  are  not  to  be  seen  after  complete  fusion  of  the  nuclei.  One 
division  of  at  least  some  of  the  nuclei  in  the  antheridium  occurs,  followed 
by  a  slow  degeneration  of  some  of  them. 

Miicke  has  since  studied  oogenesis  in  this  species  (’08)  and  fully 
confirmed  the  occurrence  of  fertilization,  but  denies  that  there  is  a  sec¬ 
ond  division  in  the  oogonium  or  a  reduction  of  chromosomes  before 
fertilization.  Work  by  Claussen  and  Davis  on  Saprolegnia  and  by 
Kasakanowsky  on  Aphanomyces  shows  only  a  single  nuclear  division 
in  the  oogonium  and  leads  us  to  believe  that  Trow  was  wrong  in  this 
respect,  though  clearly  vindicated  in  his  hard-fought  contention  for 
sexuality  in  the  Saprolegniaceae .  Miicke  concludes  that  there  are  more 
than  eight  chromosomes  in  the  nuclei  of  the  oogonia,  the  number  being 
undetermined.  He  also  claims  that  the  centrosome  is  inside  the  nuclear 
membrane  and  not  outside  it,  as  Trow  thought,  and  that  the  centrosome 


ACHLYA  143 

is  not  comparable,  as  Davis  claims,  to  the  coenocentrum  of  the  Pero- 
nosporeae. 

Achlya  prolifera  (Nees)  deBary.  Bot.  Zeit.  10:  473,  pi.  7,  figs.  1-28. 

1852. 

As  this  plant  has  not  been  found  in  America,  at  least  in  its  typical 
form,*  we  include  it  here,  and  make  the  following  translation  of  deBary ’s 
later  description  (’88,  p.  633): 

“Main  threads  stout,  usually  ending  with  primary  sporangia,  under 
which  the  secondary  are  formed  sympodially.  Oogonia  racemosely 
arranged  on  short  side  branches  of  the  main  hyphae,  as  a  rule  terminal, 
round,  the  wall  with  numerous,  very  sharply  defined  and  obvious  pits. 
Eggs  variable  in  number,  mostly  numerous,  eccentric.  Antheridial 
branches  diclinous,  much  twisted  and  branched,  winding  like  a  parasite 
about  the  oogonia  and  the  threads  which  bear  them;  the  oogonial  walls 
thickly  enwrapped  and  often  completely  covered  by  these  branches 
which  bear  numerous,  at  times  intercalary,  antheridia,  which  lay  their 
sides  against  the  oogonium  and  send  out  fertilizing  tubes. 

“The  most  abundant  of  all  Achlya  species  occurring  everywhere.” 

For  a  more  extensive  account  with  numerous  good  figures  see  deBary ’s 
first  treatment  (’81),  pi.  2,  figs.  1-2;  pi.  4,  figs.  1-4.  In  this  he  shows 
oogonia  with  eggs  varying  from  1  to  16  or  20,  but  mostly  2-3.  Also  see 
Finger  (’43),  pi.  4;  Maurizio  (’95a),  figs.  4-5;  Minden(’i2),  figs.  2b,  2d 
on  p.  520. 

For  remarks  on  this  species  see  under  A.  proliferoides  and  A.  im¬ 
perfecta.  According  to  Maurizio  (’95a),  A.  prolifera  is  often  parasitic 
on  fish.  According  to  Cienkowski  (’55),  the  eggs  may  sprout  directly 
into  zoospores. 

Achlya  aplanes  Maurizio.  Flora  79:  135,  pi.  4-5,  figs.  28-31.  1894. 

The  following  is  adapted  from  the  original: 

The  sporangia  frequently  retain  the  spores  and  in  such  cases  they 
sprout  to  threads.  No  net  sporangia  seen.  If  the  spores  emerge  they 
sprout  at  the  mouth;  and  in  no  case  do  they  have  a  swimming  stage. 
Fig.  29,  plate  5,  shows  the  spores  sprouting  at  the  tip  of  the  sporangia 
after  discharge.  .Segments  of  hyphae  often  cut  off  below  sporangia 
to  form  others.  Oogonia  racemose  (as  in  A.  prolifera )  on  short  stalks 
or  also  at  times  terminal,  intercalary  or  lateral  just  under  a  sporangium; 
spherical  (42-58.5^)  or  the  intercalary  and  end  ones  mostly  egg-  to  flask¬ 
shaped  (56  x  60[a)  ;  wall  smooth,  fairly  thick,  clear  yellowish,  usually 
with  2  or  3  pits,  or  without  any  pits.  A  young  oogonium  often  pro- 

*  Under  the  name  A.  prolifera ,  Pieters  publishes  observations  on  an  Achlya  from  Ann 
Arbor  in  the  Am.  Jour,  of  Bot.  (2:529.  1915;  also  recorded  in  Ann.  Rep.  Mich.  Acad. 
Sci.  8:  27.  1905),  but  as  his  unpublished  drawings,  kindly  submitted  to  us,  show  a  plant 
that  could  better  be  referred  to  A.  imperfecta,  we  have  noted  it  under  that  species. 


144 


THE  SAPR0LEGN1ACEAE 


liferates  to  another  one  and  empties  itself  into  it  [as  is  common  in  A. 
proliferoides ].  Eggs  I  to  12,  mostly  4  to  8,  diameter  24-31.5^,  eccentric; 
germination  not  observed.  AntheAdia  diclinous  always,  wrapping  about 
the  oogonia.  They  generally  proceed  from  more  slender  branches  that 
run  among  the  oogonial  branches.  Fertilizing  tubes  were  occasionally 
observed  entering  the  oogonia. 

Minden  thinks  this  species  should  be  united  with  A.  prolifera  if 
the  absence  of  a  swimming  stage  should  prove  not  constant.  The  eggs, 
however,  as  described  are  too  large  for  that  species,  and  approach  those 
of  A.  flagellata. 

Achlya  oligacantha  deBary.  Bot.  Zeit.  46:  647,  pi.  10,  fig.  1.  1888. 

This  species  has  been  reported  only  by  deBary,  and  the  following 
is  translated  from  the  original: 

“Main  threads  slender  and  delicate.  Oogonia  on  short  or  long 
branches  of  hyphae  which  bear  sporangia  or  in  part  terminal  on  slender 
main  threads  and  their  racemose  branches,  spherical  in  shape,  without 
an  internal  upgrowth  from  the  insertion  wall  of  the  somewhat  enlarged 
end  of  the  stalk,  surface  ahvays  with  relatively  large,  smooth,  papillae, 
which  are  separated  from  each  other  and  which  vary  greatly  in  number 
(1  to  about  16,  very  seldom  none);  also  variable  in  size  and  form  (short 
points  to  large,  blunt  projections);  wall  of  oogonia  relatively  thin,  color¬ 
less,  without  pits,  except  that  the  projections  are  mostly  thinner  than 
the  wall  between  them.  Eggs  mostly  4-8  in  an  oogonium  (seldom  up 
to  12  or  more),  round,  centric,  relatively  small.  Antheridia  always 
present,  mostly  .several  on  each  oogonium,  relatively  small,  irregularly 
spherical  to  cylindrical  with  the  side  against  the  oogonium;  borne  one 
or  two  in  a  row,  on  the  ends  of  partly  androgynous,  partly  diclinous 
antheridial  branches. 

“Brought  by  Zacharias  from  a  puddle  at  Ivork  (Baden)  with  S. 
Thureti  in  June,  1881,  and  cultivated  pure  until  1883.“ 

The  species  seems  certainly  in  the  Apiculata  group,  but  the  structure 
of  its  eggs  is  not  quite  cleared  up  by  the  word  “centric.” 

Achlya  recurva  Cornu.  Ann.  Sci.  Nat.  Bot.,  ser.  5,  15:  22.  1872. 

Since  its  first  publication  by  Cornu  this  species  has  been  reported 
only  by  Hartog,  wrho  mentions  it  without  description  (’88,  p.  212),  and  by 
Minden,  who  refers  to  it  a  plant  found  by  him  and  described  as  follows 
(’12,  p.  543): 

“Growth  extending  about  1  cm.  from  the  substratum,  with  strong 
main  threads  about  90.x  thick  at  base.  Sporangia  long,  cylindric  or 
slightly  spindleform;  secondary  ones  few.  Oogonia  numerous,  borne 
terminally  on  certain  little-branched,  often  slender  main  threads  or  on 
more  or  less  elongated,  at  times  very  long  and  branched  side  branches 
which  are  always  very  slender  and  bent  like  a  bow,  and  which  spring 


AC  FILYA 


145 


from  the  sporangia-bearing  main  hyphae;  oogonia  spherical,  rarely 
elongated  by  an  extension  of  the  tip,  and  covered  with  many  crowded, 
blunt,  hollow  projections;  diameter  of  oogonia  50-904  with  the  spines, 
the  latter  7 — 1 1  p.  long.  Antheridia  cylindrical  to  clavate,  small  on  slender 
branches,  which  are  little  or  not  at  all  branched  and  also  not  looped, 
but  mostly  only  bent  like  a  bow,  and  which  are  mostly  only  one  to  three 
to  an  oogonium,  and  are  borne  in  part  from  the  stalk  of  the  oogonium 
or  its  main  thread  or  in  part  from  other  threads.  Eggs  spherical,  1-25, 
mostly  about  10,  filling  the  oogonium,  22-274  thick. 

"Found  in  swamp  water  at  Hamburg  and  Frankreich,  and  culti¬ 
vated  on  ant  eggs.  This  seems  to  be  Cornu’s  inadequately  described 
and  therefore  doubtful  species.  It  ho'ds  a  middle  place  between  A. 
polyandra  and  A.  oligaccmtha.  It  is  like  the  former  in  the  bent  (though 
not  so  much  bent)  stalk  of  the  oogonium,  and  like  the  latter  in  the  papil¬ 
late  oogonial  wall.  The  outgrowths  on  the  oogonia  are  here  much  more 
numerous  than  in  that  species,  mostly  of  about  equal  length,  but  rarely 
one  may  be  more  developed  than  the  others.” 

The  following  incomplete  diagnosis  is  all  that  is  given  by  Cornu : 

"This  Achlya  is  distinguished  from  others  by  its  spiny  oogonia,  not 
pitted,  borne  on  a  branch  bent  in  an  arch,  toward  the  end  of  which  it 
arises  singly  and  in  general  laterally;  the  lateral  branches  arising  either 
from  the  branch  or  the  axis.  The  number  of  eggs  is  usually  from  six  to 
eight.  Sometimes  the  oogonium  bears  a  cylindrical  portion,  as  in Pythium, 
at  its  upper  end.” 

Achlya  Hoferi  Harz.  Allg.  Fischerei.  Zeitung.  31:  365.  1906. 

The  following  is  abstracted  from  the  original  (compare  with  A. 
Nowickii  in  doubtful  species,  p.  147) : 

"  Mycelium  luxuriant,  penetrating  deeply  into  the  skin  and  destroying 
the  tissue,  developing  on  outside  numerous  zoosporangia  and  oogonia. 
Hyphae  of  very  various  thickness,  45-604  in  the  thickest  part,  reaching 
only  it*,  in  the  finest  tips.  Threads  that  bear  the  oogonia  and  the  zoospor¬ 
angia  15-184  thick.  Sporangia  very  various  in  size,  30-100-6004  long 
and  5-204  broad.  Zoospores  occasionally  one-rowed  in  the  sporangia. 
Usually  many-rowed. 

"Oogonia  oval  or  occasionally  spherical,  75-1804  long,  45-604  thick, 
with  numerous,  hollow,  thorn-like  projections  which  are  64  broad,  6— 114 
high,  their  membrane  of  the  same  thickness  as  that  of  other  parts  of  the 
oogonium.  Eggs  spherical,  20-304  in  diameter,  the  number  varying 
from  several  (rarely  only  one)  to  over  30;  generally  about  20.  They 
are  colorless,  with  a  hard  coat,  and  very  full  of  fat  before  ripening,  as 
are  also  the  mycelium  and  stalks;  after  complete  maturity  this  fat  almost 
completely  disappears. 

"From  the  various  other  Saprolegniaceae  that  grow  luxuriantly 
on  live  fish,  as,  for  example,  Achlya  polyandra ,  A.  Hoferi  is  distinguished 


146 


THE  SAPROLEGNIACEAE 


by  its  deep  penetration  and  destruction  of  the  skin  tissues  [Hautge- 
webe].  The  fungus  is  always  accompanied  by  bacteria,  which  are 
probably  symbiotic  with  it  and  help  destroy  the  tissue.  However,  it 
must  not  be  overlooked  that  the  same  bacteria  and  other  Saprolegniacecie 
may  occur  on  the  same  fish  near  A.  Hoferi  and  not  cause  destruction 
of  tissue.  Achlya  Hoferi  probably  secretes  an  enzyme  which  attacks 
the  tissue  and  permits  the  penetration  of  the  fungus  threads  and  bac¬ 
teria. 

“The  assistant  at  the  station,  Dr.  Plehn,  reported  to  the  author 
as  follows  on  the  effects  on  the  tissue  caused  by  the  disease: 

‘After  the  fungus  gets  a  foothold  on  the  surface  it  soon  begins  to 
penetrate  deeper,  but  proceeds  only  slowly.  Only  after  weeks  is  the 
epidermis  [Oberhaut]  penetrated.  In  an  infected  carp  that  had  been 
observed  for  months  the  fungus  had  penetrated  the  entire  dermis  [Unter- 
haut],  occupying,  however,  only  the  fatty  connective  tissue  and  stop¬ 
ping  at  the  muscles.  In  the  deeper  tissues  also  indeed  in  the  dermis, 
the  fungus  is  not  dense,  and  one  sees  in  very  old  infections  only  isolated 
threads,  which  mostly  follow  the  cavities  of  the  tissue  and  run  between 
the  harder  layers  of  the  dermis.  Strangely  there  is  an  absence  of  in¬ 
flammation  in  the  neighborhood  of  the  fungus.  The  greater  and  more 
serious  disorganization  that  sometimes  occurs  in  this  infection,  when 
even  the  muscles  are  involved,  is  due  to  other  causes — the  myriads  of 
bacteria  that  are  present.’ 

“ Achlya  Hoferi  is  near  A.  oligacantha  deBary.  It  is  distinguished 
from  the  latter  by  the  entire  absence  of  antheridia,  the  more  elongated 
and  larger  oogonia,  the  mostly  larger  and  more  numerous  spores  [mean¬ 
ing  oospores  probably]. 

“Occurs  so  far  only  on  Bohemian  mirror  carp  in  February  of  this 
year.  The  inoculation  was  successful  in  the  case  of  three  carp  at  the 
Biological  Station,  Munich.” 

One  good  text  figure  on  page  366  shows  oogonia  and  blunt  tipped 
sporangia  much  larger  than  the  hyphae.  The  spines  as  shown  are  not 
sharp.  A  very  peculiar  species. 

EXCLUDED  OR  DOUBTFUL  SPECIES  NOT  MENTIONED  IN  THE  TEXT 

Achlya  leucosperma  Cornu.  Ann.  Soc.  Nat.,  Series  5,  15:  24.  1872. 

I  his  has  not  been  sufficiently  described  to  make  its  position  certain.  It  was  dis¬ 
tinguished  from  other  species,  especially  A.  prolifera,  by  having  only  two  pits  in  the  oogonium 
wall,  white  (not  brown)  eggs,  and  cylindrical  antheridia  which  stand  in  a  row  on  the  ends 
of  the  antheridial  branches.  These  characters  seem  quite  worthless  and  it  is  surprising 
that  Cornu  should  have  so  defined  a  species.  It  may  be  A.  prolifera.  All  eggs  of  wrater 
molds  look  milk-wffiite  when  seen  under  reflected  light. 


ACHLYA 


147 


Adilya  contorta  Cornu.  Ann.  Sci.  Nat.,  Series  5,  15:  25,  pi.  1,  figs.  10-15.  1872. 

Like  the  above  this  is  so  meagerly  described  as  to  be  indefinable.  Oogonia  smooth, 
borne  on  long,  spirally  twisted  branches  with  odd-looking  local  outgrowths;  eggs  averag¬ 
ing  8  in  an  oogonium;  antheridia  cylindrical,  branched  [compare  A.  proliferoides]. 

Adilya  dioica  Pringsheim.  Jahrb.  f.  wiss.  Bot.  2:  211,  pi.  23,  figs.  1-5.  i860. 

This  is  a  name  given  to  a  lot  of  hyphae  of  an  Adilya  without  oogonia,  and  attacked  by 
Woronina  polycystis.  It  has  no  validity. 

Adilya  penetrans  Duncan.  Proc.  Roy.  Soc.  London  25:  238.  1876. 

This  is  probably  a  Siphonaceous  alga,  as  Humphrey  thinks. 

Adilya  oidifera  Horn.  Ann.  Myc.  2:  231,  fig.  20.  1904. 

The  following  is  adapted  from  the  original: 

Growth  good  on  flies,  mealworms,  etc.,  and  in  pea  extract,  hyphae  about  4511,  thick 
in  the  latter  medium;  sporangia  and  zoospores  produced  in  abundance,  but  oogonia  nearly 
always  absent — not  formed  in  numerous  cultures  on  various  media,  such  as  agar-agar, 
haemoglobin,  leucin,  and  numerous  other  media  that  easily  produce  oogonia  in  Adilya 
polyandra  and  Saprolegnia  mixta;  oogonia  formed  only  once  and  then  in  the  inside  of  an 
ant  pupa.  They  were  spherical,  vaiied  in  size,  and  had  numerous  pits.  Eggs  2-8  in  an 
oogonium,  and  with  fat-droplets  on  one  side.  Antheridia  not  observed  with  certainty  as 
the  oogonia  were  too  old  when  found.  The  egg-like  gemmae  [oidienartiger  Zerfall]  pro¬ 
duced  in  chains  (hence  the  name),  and  forming  spores  w  hen  brought  into  pure  water;  cap¬ 
able  of  growth  after  a  long  rest  (over  a  month)  as  in  other  species. 

The  author  suggests  that  on  account  of  the  formation  of  eggs  inside  the  substratum 
this  species  may  represent  a  transition  towards  the  Peronosporaceae,  and  that  only  in  cer¬ 
tain  peculiar  conditions  not  yet  understood  will  eggs  be  produced. 

From  the  above  it  will  be  seen  that  this  species  is  insufficiently  described  and  in  need 
of  further  study.  It  must  be  considered  doubtful,  as  Minden  remarks. 

Adilya  ocellata  Tiesenhausen.  Arch.  f.  Hydrobiologie  und  Planktonkunde  7:  287,  fig.  14. 

1912. 

“Turf  stiff,  not  thick.  3  mm.  broad,  main  threads  up  to  175^  thick  at  base.  Sporangia 
as  usual.  Oogonia  raeemosely  borne  on  the  more  or  less  thickened  hyphae.  Stalks  rarely 
up  to  62[x  long,  mostly  shorter  than  the  diameter  of  the  oogonia,  at  times  absent  with  oogonia 
sessile  or  intercalary;  oogonia  40-1 18a  thick,  spherical,  rarely  pyriform,  wall  smooth  with 
evident  pits  of  medium  size.  Eggs  17. 5-25^  thick,  with  a  small  brightly  refractive  oil 
drop  that  is  very  characteristic,  5-20  or  more  in  an  oogonium,  01  rarely  one.  Antheridia 
on  branches  5-8[jl  thick,  which  are  androgynous  or  diclinous  from  nearby  threads.” 

Found  near  Campfer,  Oberengadin,  Switzerland.  Another  form  found  near  the  same 
place  had  very  short  oogonial  stalks,  otherwise  like  the  first. 

The  author  states  that  the  species  is  very  near  A.  americana  but  differs  in  the  some¬ 
times  diclinous  antheridia  and  in  the  peculiar  shining  drop'et  in  the  eggs  w'hich  is  very 
different  in  appearance  from  the  eccentric  egg  of  A.  americana.  As  the  author  does  not 
mention  any  other  member  of  the  Prolifera  group  and  gives  no  evidence  of  having  seen 
any  other  of  them  it  seems  more  than  likely  that  he  makes  all  this  ado  over  the  typical 
eccentric  egg  of  the  group.  From  his  figure  and  description  it  is  probable  that  his  plant 
is  A.  americana. 

Adilya  Nowickii  Raciborski.  Sitzungsber.  d.  Krokaner  Akad.  d.  wiss.  14:  149-168,  pi.  3. 

1886. 

We  have  not  seen  the  original,  which  is  in  Polish,  and  take  the  following  from  Minden 
in  Krypt.  FI.  Mark  B.  5:  553.  1912. 


148 


THE  SAPROLEGNIACEAE 


“Sporangia  in  plain  cymose  arrangement,  spindle-shaped,  relatively  broad,  36-804  long. 
Oogonia  75-1004  long,  45-1104  broad,  numerous,  ellipsoidal  in  outline,  but  set  with  large, 
irregular,  scattered,  hollow  projections  5-184  long.  Eggs  spherical,  3.5-74  thick  [probably 
misprint].  Antheridia  absent.  With  S.  monoica  on  a  sink  carp.” 

Minden  says  that  he  has  not  seen  the  Polish  paper,  but  thanks  Professor  Lindau  for 
the  information,  and  adds:  “In  the  form  of  the  oogonia  apparently  near  A.  cornuta  Archer 
and  A.  Hoferi  Harz.”  Under  the  last  species  he  says  that  it  may  be  identical  with  A. 
Nowickii. 

Adilya  sp.? 

Tiesenhausen  (T 2,  p.  288,  no  figures)  describes  a  sterile  form  that  he  does  not  try 
to  place.  It  is  notable,  he  says,  for  the  great  variety  of  forms  assumed  by  the  hyphae. 

THRAUSTOTHECA  Humphrey,  1892  [1893],  p.  131. 

Main  threads  stout,  branching;  sporangia  terminal,  stout,  typically 
short-clavate,  liberating  the  spores  by  cracking  and  disintegrating;  spores 
encysting  before  escaping  and  remaining  clustered  where  liberated,  af¬ 
ter  a  rest  escaping  and  swimming  with  two  lateral  cilia,  again  coming 
to  rest  and  encysting  before  sprouting.  Oogonia  single,  commonly  ter¬ 
minal  on  short  lateral  stalks,  spherical,  smooth,  weakly  pitted  or  with¬ 
out  pits;  eggs  rather  few,  eccentric.  Antheridia  diclinous,  occurring 
on  all  oogonia.  Fertilization  probably  occurs  but  has  not  been  demon¬ 
strated.  There  is  but  one  species  (but  see  Achlya  dubia). 

Thraustotheca  clavata  (deBary)  Humphrey.  Trans.  Am.  Phil.  Soc. 
17:  1 3 1 .  1892  [1893]. 

Dictyuchus  clavatus  deBary.  Bot.  Zeitung  46:  649,  pi.  9,  fig.  3. 
1888.* 


Plate  51 

Main  hyphae  stout,  straight,  reaching  a  length  of  2  cm.  in  strong 
cultures  and  a  thickness  of  20-1204,  averaging  about  374;  profusely 
branching  into  secondary  hyphae  near  their  tips;  secondary  hyphae 
much  curved  and  twisted,  and  often  curiously  knobbed  and  gnarled, 
as  shown  in  fig.  1.  Sporangia  37-85  x  66-3704,  terminal  or  rarely  inter¬ 
calary,  proliferating  as  in  Achlya ,  usually  short,  broad,  and  clavate,  but 
often  elongated  somewhat  as  in  Pythiopsis  or  even  as  in  Saprolegnia, 
varying  from  nearly  spherical  to  fusiform,  differing  from  the  sporangia 
of  any  other  of  the  Saprolegniaceae.  Spores  about  12.5-4  thick,  en¬ 
cysting  within  the  sporangium  immediately  after  they  are  formed,  and 
liberated  passively  and  slowly  by  the  gradual  cracking  and  disintegration 
of  the  sporangium  wall,  which  is  probably  due  to  internal  pressure.  They 
now  emerge  from  their  cysts  and  swim  actively  in  a  laterally  biciliate 
form,  encyst  again  and  sprout.  In  the  sporangium  they  are  polyhedral 
in  shape,  through  pressure,  each  having  a  hyaline  membrane  of  its  own. 

*The  species  was  really  first  published  incidentally  by  Biisgen  in  1882,  p.  261,  pi.  12, 
figs.  1-8,  who  in  his  study  of  the  development  of  the  sporangia  described  it  sufficiently  under 
the  name  of  Dictyuchus  clavatus  deBary  sp.  nov. 


PLATE  51 


PLATE  51 


(From  Mycologia  4:  PI.  63.  1912.) 

Thraustotheca  clavata 

Fig.  I.  Tip  of  a  main  hypha  showing  the  gnarled  condition  of  the  secondary  hyphae.  X 
1 55- 

Fig.  2.  Main  hypha  showing  sporangia  and  method  of  growth.  X  155. 

Fig.  3.  Spores  encysted  within  the  thin-walled  sporangium.  X  700. 

Fig.  4.  Spores  falling  apart,  the  basal  ring  remaining.  X  700. 

Fig.  5.  An  unusually  large  basal  cup  with  a  few  spores  still  remaining  in  it.  X  700. 

Fig.  6.  Oogonium  containing  fully  ripe  eggs.  Empty  antheridia  attached  to  the  wall  of 
the  oogonium.  X  700. 

Fig.  7.  Young  oogonium  with  antheridium  full  of  protoplasm.  X  700. 

Fig.  8.  Showing  double  branching  below  the  sporangia;  antheridial  branches;  and  proli¬ 
ferating  oogonia.  X  700. 

Fig.  9.  A  proliferating  oogonium.  X  700. 

Fig.  10.  Oogonium  with  maturing  eggs.  X  700. 


PLATE  51 


THRAUSTOTHECA 


J49 


Occasionally  among  the  ordinary  spores  large  irregular  spore  masses  are 
liberated.  These  masses  slowly  round  up  somewhat  and  encyst,  sprout¬ 
ing  later  without  a  swimming  stage.  Gemmae  small,  pyriform  or  rarely 
spherical,  falling  into  spores  in  suitable  environment.  Oogonia  borne 
singly  on  short,  straight,  perpendicular  stalks  from  the  secondary  hy- 
phae,  rarely  from  the  primaries;  30-70^  thick,  spherical,  smooth,  and 
very  slightly  pitted,  the  pits  appearing  only  after  staining  with  chlor- 
zinciodide.  Eggs  1-10  or  rarely  11,  usually  4-6  or  8,  eccentric,  with 
a  single  large  peripheral  oil  globule;  size  very  constant,  the  diameter 
about  1 8-224.  Antheridial  branches  diclinous,  arising  from  the  sec¬ 
ondary  hyphae,  very  crooked,  and  quite  stout;  antheridia  club-shaped, 
cut  off  by  a  wall;  antheridial  tubes  obvious. 

Rare.  Found  in  such  places  as  spring  below  Cobb  Terrace,  Arbore¬ 
tum  spring  and  branch,  and  in  marsh  on  south  edge  of  Glen  Burnie 
meadow.  Known  in  America  from  Chapel  Hill,  N.  C.,  and  Great  Bar¬ 
rington,  Mass.  For  other  illustrations  see  Biisgen  (’82),  figs.  1-8; 
Minden  (’12),  fig.  7  on  P-  556;  and  Weston  (T8),  pis.  4  and  5,  and  two 
text  figures. 

The  actual  fertilization  of  the  egg  has  not  been  seen,  but  we  have 
observed  the  antheridia  to  become  empty  during  the  ripening  of  the 
eggs.  In  no  case  was  it  found  that  an  antheridium  became  attached 
to  an  oogonium  arising  from  the  same  hypha  as  itself,  but  occasionally 
an  antheridial  branch  may  arise  from  the  stalk  of  one  oogonium  and 
extend  to  another  from  a  different  hypha,  thus  proving  the  plant  not 
to  be  dioecious.  When  the  eggs  first  round  up  they  show  many  oil 
globules  situated  on  one  side  (fig.  10).  These  globules  are  at  first  only 
about  2 [j.  in  diameter,  but  they  gradually  fuse  until  there  are  only  two 
or  three  larger  ones  from  84  to  154  in  diameter.  Finally  these  globules 
fu  se  into  a  single  one,  which  is  about  164  in  diameter,  and  situated  at 
the  periphery  of  the  egg.  The  eggs  are  then  ripe.  In  contaminated 
cultures  an  oogonium  will  often  sprout  a  new  one,  the  old  being  emptied 
into  the  new  (fig.  9).  This  process  may  be  repeated  several  times  and 
the  eggs  be  formed  finally  in  the  terminal  oogonium  (fig.  8).  Occa¬ 
sionally  two  oogonia  are  produced  upon  one  branch. 

After  the  encysting  of  the  spores,  the  sporangial  wall,  which  has 
always  been  thin,  breaks  and  begins  to  disappear,  vanishing  first  as  a 
rule  on  one  side  near  the  end,  and  continuing  to  disintegrate  until  nothing 
is  left  of  it  except  a  narrow  circular  ring  at  the  base.  This  basal  ring  may 
be  quite  conspicuous  or  almost  entirely  absent.  Except  in  A.  dubia  this 
method  of  dehiscence  is  entirely  unique  in  water  molds  and  is  superficially 
like  that  of  the  mold  Mucor  and  its  relatives.  This  resemblance  was 
remarked  on  at  the  time  the  plant  was  described,  and  Solms-Laubach 
thought  he  saw  another  point  of  agreement  between  Mucor  and  our  plant 
in  the  upward  bulging  of  the  basal  partition.  The  bulging  is,  however. 


THE  SAPROLEGNIACEAE 


150 


imaginary,  and  if  present  at  all  is  no  more  pronounced  than  in  other  water 
molds. 

The  species  has  been  reported  only  a  few  times  (by  Biisgen,  by  Min- 
den,  by  Weston,  and  by  us)  since  its  first  discovery.  DeBary  got  his 
material  from  a  collection  taken  in  1880  by  Stahl  from  a  fresh-water 
lake  at  Vendenheim  near  Strassbourg,  Germany,  and  kept  it  growing 
in  his  laboratory  for  four  years. 

On  account  of  the  unparalleled  method  of  spore  liberation  it  was 
suggested  by  Solms-Laubach,  who  after  deBary’s  death  arranged  and 
edited  his  last  paper,  that  this  species  might  be  considered  as  generically 
distinct  from  the  other  species  of  Dictyuchus.  This  was  again  remarked 
on  by  Fischer  (’92,  p.  365),  and  the  next  year  Humphrey  was  sufficiently 
impressed  with  its  distinction  to  give  it  generic  rank. 

For  our  first  account  of  this  species,  from  which  this  is  taken  in 
great  part,  and  from  which  the  plate  is  copied,  see  Mycologia  4:  87,  pi.  63. 
1912.  The  most  detailed  study  yet  given  to  the  plant  is  by  Weston 
(T8).  He  thinks  that  the  sporangium  wall  breaks  from  the  swelling 
of  the  spores  and  that  its  fragility  has  been  greatly  over-emphasized. 
Weston  also  observed  sprouting  of  the  eggs,  which  may  form  either 
sporangia  or  an  extensive  mycelium,  depending  on  the  amount  of  nutri¬ 
ment  available. 

All  the  following  cultures  were  made  from  No.  10  of  January  30, 
1913: 

In  equal  parts  of  maltose  5%  and  peptone  .01%.  Extensive  growth.  A  few  sporangia 
formed.  Spores  sprouting  in  position.  A  large  number  of  oogonia  initials  but  none 
maturing  eggs.  Most  were  more  or  less  inflated.  Some  sent  out  sprouting  tubes, 
others  went  to  pieces  inside.  Culture  repeated  with  similar  results. 

On  corn  meal  agar.  Growth  luxuriant.  Many  sporangia  formed,  often  in  rows  like  gemmae, 
but  all  forming  spores  and  falling  to  pieces.  Culture  duplicated  with  same  results. 

On  yolk  of  egg  in  distilled  water.  Strong  vigorous  growth.  Great  number  of  good  sporangia. 

A  good  many  oogonia,  only  a  few  of  which  matured  their  eggs. 

On  white  of  egg  in  distilled  water.  Vigorous  growth.  Only  sporangia  formed  and  they 
not  so  abundant.  Some  of  them  seemed  to  dissolve  and  become  surrounded  by  bac¬ 
teria. 

In  addition  to  these  many  cultures  were  made,  of  course,  on  insects,  etc.,  with  normal 
results. 

A  pure  culture  on  corn  meal  agar  was  put  in  a  vial  on  March  15,  1913,  and  was  found  to  be 
dead  December  1,  1913. 

A  pure  culture  was  put  in  an  aquarium  jar  with  algae  in  the  laboratory  in  March,  1913. 
When  tested  for  life  September  18,  1917,  no  growth  appeared. 

DICTYUCHUS  Leitgeb,  1868,  p.  503. 

Vegetative  structure  and  appearance  as  in  Achlya,  but  of  much 
more  tardy  development  in  cultures  (at  least  in  D.  sterile ) ;  tips  of  hyphae 


DICTYUCHUS 


151 

rather  blunt.  Primary  sporangia  nearly  cylindrical,  blunt,  borne  typi¬ 
cally  in  a  zigzag  sympodium  with  long  internodes;  later  they  are  formed 
by  the  segmentation  of  the  hyphae  into  long  joints  and  in  such  case, 
after  the  spores  are  formed,  rest  like  gemmae  for  a  change  of  media 
before  liberating  the  spores,  and  show  a  strong  tendency  to  fall  away 
from  each  other  and  from  the  hyphae  and  to  lie  free  in  the  water.  Spores 
not  escaping  from  the  sporangium  as  in  other  genera  (except  Aplanes), 
but  remaining  in  the  sporangium  and  forming  there  a  network  of  walls 
from  which  they  emerge,  after  a  rest,  by  individual  openings  to  the  out¬ 
side,  where  they  swim  by  two  cilia  and  in  the  form  of  the  second  swimming 
stage  in  Saprolegnia.  They  then,  as  a  rule,  sprout  as  usual  in  the  family 
but  Weston  (’19)  has  shown  that  some  of  them  may  again  emerge  and 
swim  before  sprouting.  Gemmae  not  represented  unless  the  resting 
sporangia  with  spores  in  them  be  considered  such.  Oogonia  spherical, 
smooth,  the  wall  unpitted,  terminal  on  slender  branches  (absent  (?)  in 
D.  sterile).  Antheridia  much  as  in  Saprolegnia  and  Achlya ,  diclinous 
or  androgynous;  fertilizing  tubes  observed.  Eggs  one  to  many,  not 
filling  the  oogonium,  at  maturity  containing  one  or  a  few  large  oil  drops 
inside  the  protoplasm. 


Key  to  the  Species.* 

Oogonia  unknown  (plant  never  fruiting) ;  sporangia  apt  to  drop  off  in  a  resting  state 

D.  sterile  (1) 

Oogonia  with  one  egg 

Antheridia  and  antheridial  branches  not  surrounding  the  oogonia . D.  Magnusii  (2) 

Antheridia  with  the  antheridial  branches  often  thickly  encircling  the  oogonia 
Hyphae  here  and  there  branched  in  a  normal  way;  eggs  centric 

D.  monosporus  (p.  156) 

Hyphae  with  irregularly  arranged,  mostly  short,  papillose  outgrowths  with  an  abnormal 

appearance;  eggs  eccentric .  D.  carpophorus  (p.  157) 

Oogonia  with  many  eggs . . . .  D.  polys por us  (p.  157) 


i.  Dictyuchus  sterile  n.  sp. 

Plate  52 

Vegetative  growth  moderately  stout.  Main  hyphae  branching,  up 
to  55[j.  thick,  mostly  30-45 p.  at  base,  very  gradually  tapering  towards 
end,  the  larger  up  to  22-370.  near  tip,  many  much  smaller.  Primary 
sporangia  borne  on  the  tips  of  hyphae,  later  ones  formed  by  cymose 
branching,  but  usually  separated  from  the  earlier  ones  by  some  distance 
by  the  elongation  of  the  threads.  As  the  culture  ages  the  arrangement 
becomes  more  irregular  and  complicated  and  most  of  the  threads  become 
segmented  towards  the  periphery  into  numerous  sporangia  in  rows  or 

*Taken  from  Minden,  except  for  the  addition  of  the  Chapel  Hill  plant.  The  American 
species  are  followed  by  a  number,  the  others  by  a  page  reference. 


152 


THE  SAPROLEGNIACEAE 


branched  groups.  They  are  usually  a  little  larger  in  the  distal  half,  often 
bent,  sometimes  branched,  of  various  size,  in  old  cultures  often  very 
long,  not  rarely  thread-like  with  only  a  single  row  of  spores.  They 
usually  break  off  from  the  hyphae  about  the  time  the  outline  of  the  spores 
becomes  distinct  and  go  into  a  resting  state  which  may  last  a  few  days 
or  many  weeks  depending  on  conditions.  During  this  time  the  spores 
are  separated  by  walls  which  in  this  condition  are  scarcely  visible,  the 
individuality  of  the  spores  being  indicated  by  the  usually  conspicuous 
vacuole  that  each  contains.  On  emerging  the  spores  escape  singly 
and  swim  as  normal  in  the  genus  or  they  often  sprout  in  position  into 
slender  hyphae.  Spores  ii.8-i6.6jji  in  diameter  before  sprouting,  with 
large  conspicuous  vacuole.  Oogonia  not  developed. 

Plentiful  in  springs  and  small  streams,  such  as  Arboretum  spring 
and  brook,  Battle’s  branch,  branch  back  of  athletic  field,  etc.  Col¬ 
lected  63  times  from  February,  1912,  to  December,  1913  (see  table  on  p.  14) ; 
also  found  many  times  since.  The  plant  has  a  way  of  appearing  tardily 
and  often  turns  up  in  old  cultures.  In  our  collection  notes  it  often  may 
have  missed  being  listed,  because  the  culture  was  not  kept  long  enough. 

The  resting  stage  is  not  of  fixed  length,  but  may  be  brought  to  an 
end  at  any  time  by  a  change  of  environment,  such  as  by  putting  a  cover 
glass  over  a  resting  sporangium  or  by  a  change  of  water.  If  the  original 
culture  remains  undisturbed  the  sporangia  may  continue  in  the  resting 
condition  practically  indefinitely,  that  is,  for  several  months.  The 
falling  oft  of  the  sporangia  begins  while  the  plant  is  still  in  active  growth, 
and  as  age  approaches  the  protoplasm  may  practically  all  be  used  up 
in  the  formation  of  such  sporangia  (see  also  Weston,  ’19,  p.  290).  This 
deciduous  habit  is  found  also  in  D.  monosporus,  and  is  mentioned  both  by 
Leitgeb  (’69,  p.  366)  and  by  Minden  (’12,  p.  566).  According  to  the 
former  this  habit  appeared  only  after  cultivating  the  fungus  for  two 
months,  but  Minden  finds  it  occurring  regularly  in  the  same  species  and 
does  not  consider  it  a  result  of  degeneration.  This  species  has  been 
watched  by  us  for  twelve  years  and  though  grown  on  a  great  variety  of 
media  it  has  never  been  observed  to  form  oogonia,  antheridia,  or  gemmae 
other  than  the  resting  sporangia,  if  such  might  be  considered  gemmae. 

Of  the  four  described  species  in  this  genus  our  plant  seems  most 
like  D.  monosporus  and  D.  polysporus,  the  sporangia  being  exactly  as  fig¬ 
ured  by  Leitgeb  for  the  former  and  by  Lindstedt  for  the  latter,  and  in  the 
former,  as  mentioned  above,  they  tend  to  fall  off  in  a  resting  state.  There 
are  objections  to  establishing  a  species  or  variety  on  the  basis  of  the  vege¬ 
tative  and  asexual  reproductive  characters  alone,  but  the  very  positive 
sterility  of  our  plant  over  a  series  of  ten  years  of  cultures  in  various  media, 
representing  over  a  hundred  findings,  would  seem  to  justify  naming  it,  if 
for  no  other  reason  than  convenience.  The  same  plant  to  all  appearances 
is  found  in  other  places  and  is  probably  wide-spread.  We  take  it  to  be  the 


PLATE  52 


PLATE  52 

Dictyuchus  sterile  n.  sp. 

Fig.  I.  Part  of  a  sporangium  showing  net  and  two  spores  in  act  of  emerging.  X  533- 
Fig.  2.  Spore  with  two  cilia.  X  533- 

Fig.  3.  Part  of  a  sporangium  with  two  spores  in  amoeboid  movement.  X  533. 

Fig.  4.  Spores  sprouting  in  the  sporangium.  X  319. 

Fig.  5.  Sporangia  in  resting  state,  one  free,  another  falling  off.  X  18S. 

Fig.  6.  Spores  formed  in  small  sporangia.  X  188. 

Fig.  7.  Sporangium  entirely  empty  of  spores,  thus  leaving  a  “net  sporangium.”  X  319. 
Fig.  8.  Sporangia  in  resting  state.  X  113. 

Fig.  9.  Showing  characteristic  branching  of  hyphae  and  atrophied  growing  points  (a) 
renewed  from  below.  X  188. 

Fig.  10.  Resting  sporangium  of  peculiar  shape.  X  188. 

Fig.  11.  Resting  sporangium  from  which  a  few  spores  have  emerged.  X  188. 


PLATE  52 


DICTYUCHUS  STERILE 


DICTYUCHUS 


153 


same  as  the  first  mentioned  of  the  two  sterile  plants  noted  by  Humphrey 
on  p.  133  of  his  monograph,  though  he  does  not  mention  the  deciduous 
sporangia.  Dr.  I.  F.  Lewis  tells  us  that  he  has  seen  a  similar  form  in 
Virginia,  and  Weston  (’19)  has  described  a  second  swimming  stage  in 
a  sterile  plant  that  he  finds  in  Massachusetts.  We  have  little  doubt  that 
his  plant  is  the  same  as  ours,  not  only  from  its  sterility,  but  because  a 
sporangium  is  shown  nearly  loosened  from  its  hypha  (fig.  19).  Weston’s 
good  figures  of  detail  in  the  spores  and  their  emergence  should  be  con¬ 
sulted.  Both  Tiesenhausen  (’12,  p.  289,  figs.  15-18)  and  Minden  (’12) 
find  a  sterile  plant  in  which  the  sporangia  fall  off,  which  is  probably  the 
same  as  ours  in  both  cases.  Minden  refers  his  sterile  plant  to  D.  mono- 
sporus,  but  this,  of  course,  could  not  be  convincingly  done  without  a 
knowledge  of  the  sexual  organs. 

The  situation  is  indeed  interesting  and  perplexing.  Leitgeb  (’69) 
found  that  sporangia  appeared  on  both  the  male  and  female  threads 
of  D.  monos por us;  he  also  found  a  sterile  plant  (species  unknown,  perhaps 
the  same  as  ours)  in  which  only  sporangia  were  formed  during  four  months  ’ 
cultivation.  On  the  other  hand,  Lindstedt  never  found  any  sporangia 
on  male  or  female  threads  of  D.  Magnusii,  and  speaks  of  his  plant  as 
trioecious  for  that  reason  (1.  c.,  p.  16).  It  seems  to  us  to  be  very  signifi¬ 
cant  that  in  all  cases  a  Dictyuchus  that  started  out  to  be  sterile  has 
remained  so  consistently,  and  thus  has  never  been  proved  to  be  the  same 
as  a  fertile  species,  while  all  fertile  species  have  been  fruitful  from  the 
first. 

With  the  exception  of  D.  polysporus,  which  is  of  more  than  doubt¬ 
ful  validity,  all  of  the  species  are  known  to  be  diclinous,  and  it  may  be 
that  we  have  here  a  real  dioecious  plant  (if  so  the  only  one  in  the  family). 
In  such  case  it  might  be  possible  that  one  of  the  sexes  could  come  to  oc¬ 
cupy  alone  an  extensive  territory  by  asexual  reproduction,  with  apparent 
sterility  as  a  result.  This  is,  however,  very  improbable  as  in  no  other 
species  of  the  family  is  the  presence  of  antheridia  necessary  for  the  ap¬ 
pearance  of  the  oogonial  initials.  We  have  at  various  times  put  together 
cultures  from  different  sources  in  the  Chapel  Hill  region  in  an  effort  to 
settle  this  point,  but  always  without  result.  If  sexual  reproduction 
should  ever  be  found  in  our  plant  and  be  similar  to  that  of  a  known 
species,  its  extreme  sterility  would  still  entitle  it  to  recognition  as  a  vari¬ 
ety  or  race. 

Cultures  from  No.  13  of  November  7,  1912: 

In  maltose  5%+  peptone  .01%.  Growth  was  fairly  strong,  but  not  over  inch  in  diameter. 
The  protoplasm  in  many  of  the  hyphae  was  segregated  into  little  clumps,  as  in 
Adilya  hypogyna  in  several  media.  Many  spores  were  formed.  After  two  weeks  the 
culture  was  still  alive,  with  many  hyphae  of  normal  appearance. 


154  THE  SAPROLEGNIACEAE 

On  ant  in  spring  water.  Growth  healthy,  limited  to  inch  diameter.  Many  resting 
sporangia,  which  were  observed  to  rest  for  nearly  a  month. 

On  ant  in  distilled  water.  As  above  except  growth  of  about  ^4  inch  in  diameter  and  fewer 
sporangia. 

On  ant  in  rain  water.  Exactly  as  in  spring  water  above. 

On  corn  meal  egg  yolk  agar.  Growth  strong,  covering  dish.  An  immense  number  of  spor¬ 
angia. 

Resting  sporangia  were  taken  from  No.  I  of  May  I,  1913,  and  put  under  a  cover  on  slide 
to  test  again  the  emergence  under  such  conditions.  In  H  hour  the  spores  had  begun 
to  emerge  in  good  number.  After  escaping  they  would  tremble  and  jerk  and  turn 
for  several  minutes  and  then  swim  away. 

At  another  time  the  following  notes  were  made: 

Six  minutes  after  emergence  the  spores  began  to  move  slightly,  in  18  minutes  there  was 
violent  motion  and  in  40  seconds  more  the  spores  tore  loose  and  swam  away.  The 
cilia  became  visible  in  living  state  in  15  minutes  after  emergence. 

In  .05%  haemoglobin.  Vegetative  growth  luxuriant.  Sporangia  sparingly  formed. 
Hvphae  seldom  branching. 

In  K6H3(P04)2+haemoglobin.  Vegetative  growth  was  luxuriant — more  than  above. 
The  hyphae  twisted  in  their  course  and  sent  off  many  lateral  branches  almost  at  right 
angles.  Sporangia  exceedingly  abundant.  At  last  all  protoplasm  of  plant  seemed 
to  be  used  in  forming  sporangia. 

In  KNO3  +  haemoglobin.  Growth  was  about  normal  with  hyphae  not  quite  so  crowded. 
Sporangia  were  formed  in  considerable  numbers  at  the  tips  of  the  hyphae.  Vacuoles 
scattered. 

In  KC1  +  haemoglobin.  Growth  was  very  sparse.  Hyphae  frequently  branched,  forming 
sporangia  at  tips.  The  protoplasm  of  the  hyphae  always  exceedingly  dense. 

In  MgSCh  +haemoglobin.  Growth  very  sparse.  Sporangia  formed.  Hyphae  rarely 
branching. 

Experiments  to  determine  the  best  method  of  preserving  live  cul¬ 
tures: 

Culture  of  No.  13  of  December  7,  1912,  put  in  aquarium  jar  with  algae  in  laboratory  on 
February  19,  1913.  When  tested  for  life  on  September  18,  1917.no  growth  appeared. 
Culture  of  No.  13  of  December  7,  1912,  put  in  vial  on  corn  meal  agar  on  March  18,  1913. 
When  tested  on  December  1,  1913,  it  was  found  to  be  alive.  It  is  of  interest  to  note 
that  of  the  sixteen  species  tested  in  this  way  at  this  time  none  was  found  to  be  alive 
except  Dictyuchus. 

Experiments  begun  January  15,  1913,  show  that  Dictyuchus  will 
not  grow  at  all  on  pea-broth-gelatine,  on  which  all  species  of  Saprolegnia 
grow  profusely;  nor  will  Dictyuchus  grow  on  acidified  beef  agar  or  on 
plant  decoctions  such  as  prune  juice,  Baccharis  twigs,  etc. 

2.  Dictyuchus  Magnusii  Lindst.  Synopsis  de  Saprol.,  p.  7,  pi.  1,  figs. 
1-13.  1872.* 

Plate  53 

This  has  been  reported  only  by  Humphrey  (’92,  p.  132,  pi.  20,  figs. 
112-114)  from  preparations  made  by  Trelease.  But  Pieters  has  found 


¥d  he  condensed  specific  description  is  on  page  18. 


PLATE  S3 


PLATE  53 

(Drawn  by  Dr.  A.  J.  Pieters) 

Achlya  polyandra 
Figs.  1-4.  Oogonia  with  antheridia. 

Fig.  5.  Unusual  form  of  oogonium  with  spines.  No.  4  from  Ann  Arbor,  Michigan;  others 
from  Heidelberg,  Germany. 

Dictyuchus  Magnusii 

Fig.  6.  Oogonium  with  nearly  mature  egg.  X  525. 

Fig.  7.  Sporangia. 

Figs.  8-9.  Oogonia  with  antheridia  and  young  eggs.  X  525. 

Fig.  10.  Oogonium  without  antheridia.  X  525. 

Figs.  1 1— 13.  Sporangia.  All  from  Ann  Arbor,  Michigan. 


PLATE  53 


ACHLYA  POLYANDRA.  [FIGS.  1-5.]' 
DICTYUCHUS  MAGNUSII.  [FIGS.  6-13] 


DICTYUCHUS 


x55 


in  Michigan  a  plant  which,  from  his  unpublished  description  and  drawings, 
we  take  to  be  this  species  (reported  as  D.  monosporus  in  Ann.  Rep.  Mich. 
Acad.  Sci.  17:  195.  1915).  With  his  consent,  we  are  using  Dr.  Pieters ’s 

pencil  drawings  in  plate  53. 

The  following  is  from  Humphrey: 

“Hyphae  rather  large.  Zoosporangia  cylindric  or  fusiform.  Oo- 
gonia  terminal  on  slender  branches,  globular,  smooth-walled,  unpitted. 
Antheridia  cylindric  or  slightly  clavate,  on  all  oogonia,  borne  on  slender 
branches  of  diclinous  origin.  Oospores  single,  centric,  about  25a  in 
diameter. 

“Massachusetts — Cambridge,  Trelease.  Europe. 

“Our  knowledge  of  the  occurrence  of  this  species  in  America  rests 
on  the  notes  and  preparations  of  Professor  Trelease,  who  obtained  it  in 
1881  from  water  in  the  Botanic  Garden,  at  Cambridge.  It  can  be  con¬ 
founded  only  with  D.  monosporus ,  from  which  it  differs  in  its  somewhat 
larger  oogonia  and  less  coiled  antheridial  branches. 

“Lindstedt  states  that  it  is  only  in  this  species  that  the  sporangia 
are  formed  from  the  hyphae  in  basipetal  succession,  but  it  seems  doubt¬ 
ful  if  this  is  strictly  true,  in  view  of  certain  observations  to  be  men¬ 
tioned  later.”  We  may  add  to  these  remarks  that  Lindstedt  also  notes 
that  the  eggs  after  a  rest  sprout  by  a  vegetative  thread  (1.  c.,  p.  18). 

Pieters  says: 

“Collected  on  a  fly,  from  water  with  algae,  in  the  Botanical  Labora¬ 
tory  at  Ann  Arbor,  November,  1913.  Oogonia  developed  on  fly  at  tem¬ 
perature  22-30°  C.  Antheridia  always  strongly  diclinous,  and  clasp 
the  oogonia  with  one  or  more  processes.  Oogonia  walls  thin,  not  pitted; 
eggs  single,  centric  with  two  to  many  oil  drops.  Sporangia  will  develop 
in  pea  agar.”  He  labels  his  notes  D.  monosporus ,  and  says  further:  “I 
will  admit  that  there  may  be  a  doubt  as  to  whether  this  species  is  mono¬ 
sporus  or  Magnusii.  I  determined  it  as  monosporus  on  the  strength 
of  the  fact  that  antheridia  coiled  around  the  oogonia.  The  size  of  the 
oogonia,  however,  appears  to  be  that  of  Magnusii  rather  than  that  of 
monosporus .” 

It  is  indeed  extremely  doubtful  if  D.  Magnusii  is  a  good  species. 
As  described  by  Lindstedt  it  differs  from  D.  monosporus  only  in  three 
characters,  none  of  which  is  of  any  value  unless  established  as  con¬ 
stant  by  a  series  of  careful  cultures — a  precaution  that  one  feels  pretty 
sure  Lindstedt  did  not  take.  These  three  points  of  difference  are  that 
in  D.  monosporus  the  oogonia  are  25;jl  thick,  the  antheridial  branches  wind 
about  the  oogonia,  and  the  sporangia  are  in  sympodia;  while  in  D.  Magnusii 
the  oogonia  are  30-35:0.  thick,  the  antheridial  branches  do  not  wind  about 
the  oogonia,  and  the  sporangia  are  borne  only  in  rows.  As  our  sterile 


156 


THE  SAPROLEGNIACEAE 


variety  unites  in  all  degrees  both  the  above  methods  of  sporangial  arrange¬ 
ment,  as  is  also  the  case  in  Humphrey’s  sterile  plant  (which  is  probably 
the  same  as  ours),  first  mentioned  on  p.  133  of  his  monograph,  there  is 
little  ground  for  taking  this  distinction  seriously.  The  other  differences 
might  easily  come  within  the  limits  of  variation  of  a  single  species,  from 
analogy  with  other  Saprolegniaceae ,  and  carry  no  conviction,  especially 
as  Lindstedt  seems  never  to  have  seen  D.  monosporus ,  with  which  he  com¬ 
pares  his  species. 

EUROPEAN  SPECIES  NOT  YET  FOUND  IN  AMERICA 

Dictyuchus  monosporus  Leitgeb.  Jahrb.  f.  wiss.  Bot.  7:  357,  pi.  22, 

figs.  1-12,  pi.  23,  figs.  1-8.  1869. 

This  has  been  reported  from  America  only  by  Pieters  (in  Kauffman, 
’15),  but  we  are  treating  his  plant  as  D.  Magnusii,  which  see.  The  following 
is  adapted  from  Fischer  (’92,  p.  362) : 

Growth  thick,  1-1.5  cm.  broad,  with  flaccid  main  hyphae  up  to 
60 p.  thick.  Sporangia  terminal,  either  long,  thread-shaped  and  little 
or  no  thicker  than  the  threads,  or  long  clavate,  250-950^  long,  18-37^ 
broad,  often  containing  only  a  single  row  of  spores;  proliferating  by 
repeated  sprouting  from  the  side  below  to  form  a  sympodium.  Spores 
bean-shaped,  9-iOtx  thick.  Oogonia  terminal,  single,  on  long  or  short 
branches  of  the  main  threads,  spherical,  25^,  in  diameter;  the  wall  uneven 
and  without  pits.  Antheridia  always  present,  usually  several  to  each 
oogonium,  borne  on  slender  branches  of  diclinous  origin  which  often 
completely  enwrap  the  oogonium.  Eggs  single,  spherical,  smooth,  cen¬ 
tric;  germination  not  known. 

Cultivated  on  insects,  or  with  ease  on  twigs,  or  on  bulbs  of  hyacinth, 
calchicum  and  tulip. 

According  to  Cornu  the  plant  grows  well  on  twigs  and  forms  very 
long  threadlike  sporangia  with  spores  in  a  single  row.  The  number  of 
spores  is  often  large — up  to  300  (Leitgeb),  up  to  600  (Cornu).  Accord¬ 
ing  to  Leitgeb  sporangia  are  borne  both  on  the  threads  which  bear  oo¬ 
gonia  and  on  the  more  slender  male  ones.  Whether  really  dioecious  or 
not  is  not  stated.  [Above  is  from  Fischer]. 

Leitgeb  had  an  interesting  experience  with  this  plant.  For  the  first 
two  months  of  culture  the  spores  escaped  normally  while  the  sporangia 
were  attached  to  the  threads,  the  empty  sporangia  falling  off  afterward. 
After  this  period  most  of  the  sporangia  fell  off  while  still  full,  as  in  our 
D.  sterile,  and  in  this  condition  the  great  majority  of  them  sprouted  as 
in  A  planes.  After  another  half  month  the  sporangia  of  all  cultures 
failed  to  mature  normal  spores,  the  protoplasm  of  the  spores  dying  soon 
after  they  were  formed.  He  thinks  this  abnormal  behavior  must  have 
been  due  to  some  peculiar  diseased  condition  that  he  was  not  able  to 
explain. 


LEPTOLEGNIA 


157 


See  also  Massee  (’91),  pi.  5,  figs.  102-104. 

Dictyuchus  carpophorus  Zopf.  Beitrage  z.  Phys.  u.  Morph.  n.  Organ- 

ismen  3:  48,  pis.  2  and  3.  1893. 

This  species,  in  spite  of  much  elaborate  description,  is  doubtfully 
distinct  from  D.  monosporus.  It  is  supposed  to  differ  in  the  numerous 
abnormal-looking  lateral  outgrowths  on  the  hyphae  and  the  eccentric 
eggs  in  oogonia  which  are  often  thickly  enwrapped  with  antheridia. 
As  shown,  the  eggs  are  what  we  are  calling  eccentric,  with  a  large  oil 
drop  in  the  protoplasm,  and  there  is  no  evidence  that  the  so-called 
centric  eggs  of  D.  monosporus  are  not  of  similar  structure. 

Dictyuchus  polysporus  Lindstedt.  Synopsis  d.  Saprol.,  p.  19,  pi.  2,  figs. 

1-3;  pi.  3,  figs.  1-7.  1872. 

This  species  has  not  been  found  since  first  reported  and  one  does 
not  feel  quite  convinced  of  its  validity.  Fischer  suggests  that  Lind¬ 
stedt  may  have  had  mixed  material  before  him.  The  sporangia  look 
exactly  like  those  of  our  D.  sterile  and  like  Leitgeb’s  figures  of  D.  mono¬ 
sporus,  but  the  antheridia  are  said  to  be  androgynous  and  the  oogonia 
have  numerous  eggs,  which  characters  are  in  sharp  contrast  to  the  di¬ 
clinous  antheridia  and  single-egged  oogonia  of  all  the  other  species. 

The  species  may  be  concisely  defined  thus: 

Growth  delicate,  the  threads  only  up  to  cm.  long.  Sporangia 
shorter  than  in  D.  monosporus ,  multiplying  by  sympodial  branching  as 
in  Achlya.  Oogonia  irregularly  arranged,  terminal  or  intercalary,  single 
or  several  in  a  row,  of  various  shapes,  spherical  or  ovate  or  long  flask- 
shaped;  wall  smooth,  without  pits.  Antheridia  androgynous,  up  to 
several  on  an  oogonium  or  absent  on  some  of  them,*  short  clavate  with 
the  side  attached  to  the  oogonium,  borne  on  usually  simple  branches  of 
rather  definite  length  which  spring  mostly  from  main  hyphae  which 
bear  oogonia;  fertilizing  tubes  present.  Eggs  2-20  in  an  oogonium, 
25-27[jl  thick. 


LEPTOLEGNIA  deBary,  1888,  p.  609. 

Hyphae  long  and  delicate,  sparingly  branched.  Sporangia  long, 
apical,  cylindrical,  of  the  same  size  as  the  hyphae,  at  times  multiplied 
by  growth  through  empty  ones,  rarely  branched.  Spores  formed  in  a 
single  row,  elongated  on  emerging,  then  changing  their  form  to  pip¬ 
shaped  and  swarming  with  two  apical  cilia,  encysting  and  swimming 


*  Lindstedt  does  not  mention  their  absence  on  some  oogonia,  but  out  of  eight  of  his 
figures  that  show  oogonia,  five  are  without  antheridia 


THE  SAPROLEGNIACEAE 


158 

again  as  in  Saprolegnia.  Gemmae  absent.  Oogonia  borne  on  short 
lateral  branches,  small,  smooth,  subspherical,  unpitted.  Antheridia  pyri¬ 
form,  diclinous.  Eggs  single,  completely  filling  the  oogonium,  the  proto¬ 
plasm  nearly  surrounded  by  a  surface  layer  of  small  droplets.  There  is 
but  one  species  known. 

Leptolegnia  caudata  deBary.  Bot.  Zeit.  46:  631,  pi.  9,  fig.  5.  1888. 

Plate  54* 

Mycelium  delicate,  flaccid,  the  hyphae  little  branched,  about  10- 
184  thick;  gemmae  none;  sporangia  filamentous,  of  the  same  size  as 
the  hyphae,  often  long  but  not  so  long  as  in  Aphanomyces,  about  15-18  X 
325-8804,  sometimes  branched;  spores  typically  in  a  single  row,  irregu¬ 
larly  angled  and  lobed  before  discharge,  becoming  rod-shaped  when 
passing  out;  after  emergence  the  two  ends  bending  backward  and  fusing 
to  form  a  pip-shaped  spore  with  two  apical  cilia;  diplanetic,  1 2.5-1 3.54 
in  diameter  in  the  resting  state.  Oogonia  borne  on  rather  short  lateral 
branches,  subspherical  with  a  slight  beak,  smooth  and  without  pits, 
30-404  thick.  Eggs  single  with  a  more  or  less  complete  circle  of  periph¬ 
eral  droplets,  completely  filling  the  oogonium.  Antheridia  one  or  several 
on  every  oogonium,  short-pyriform,  terminating  slender  branches  of 
diclinous  origin. 

Rather  rare,  first  found  in  an  aquarium  jar  of  algae  that  had  been 
brought  into  the  laboratory  from  pools  in  the  vicinity.  Occurring  in 
0.7%  of  all  Chapel  Hill  collections  between  February  15,  1912,  and  De¬ 
cember  12,  1913,  as  in  Terra  Cotta  spring,  Glen  Burnie  farm,  marsh 
south  side  of  Glen  Burnie  meadow,  Arboretum  brook,  etc.  Later  it 
appeared  in  several  collections  of  material  sent  by  R.  S.  Haltiwanger 
from  Avon  Park,  Florida,  and  in  material  collected  by  us  near  Wilmington, 
N.  C. 

Found  twice  by  deBary  in  mountain  lakes  in  Germany  in  1881  and 
1884,  the  species  has  been  reported  but  a  few  times  since.  Fischer 
(’92,  p.  346)  refers  to  a  sterile  plant  that  he  thought  might  be  this  species. 
Minden  (’12)  found  it  often  near  Hamburg,  Germany,  and  figures 
it  (figs.  4a  and  4b  on  p.  556),  and  Petersen  finds  it  in  Denmark  (To, 
p.  521).  Dr.  Roland  Thaxter  writes  that  he  has  seen  a  form  without 
sexual  reproduction  that  resembled  Leptolegnia',  and  Dr.  Pieters  has 
unpublished  drawings  of  the  characteristic  sporangia  from  plants  found 
at  Ann  Arbor,  Michigan.  According  to  Petersen  (’30,  p.  51 1)  this  species 
is  a  destructive  parasite  on  the  crustacean  Leptodora  Kindtii  in  Denmark. 
He  thinks  that  the  mycelium  usually  enters  around  the  opening  of  the 
mouth,  and  that  the  infection  is  always  fatal,  enveloping  the  mother  and 

*  See  Mycologia  1:  262,  pi.  16,  1909,  from  which  the  plate  and  most  of  the  description 
was  taken. 


PLATE  54 


PLATE  54 

(From  Mycologia  1:  PI.  16.  1909.) 

Leptolegnia  caudata 

Fig.  1.  A  branched  sporangium  with  one  opening  at  a.  X  90. 

Fig.  2.  Oogonium  with  two  antheridia.  X  370. 

Fig.  3.  Antheridium  applied  to  an  oogonium.  X  370. 

Fig.  4.  Oogonium  with  antheridium  pulled  away  leaving  a  distinct  circular  opening.  X  370. 
Fig.  5.  a.  Part  of  a  sporangium,  showing  spores  killed  in  the  act  of  emerging;  b,  c,  d,  e, 
f,  g,  h,  i  showing  spores  in  successive  stages  of  rounding  up  in  preparation  for 
swimming  off  after  emergence. 


PLATE  54 


LEPTOLEGNIA  CAUDATA. 


LEPTOLEGNIA 


159 


eggs  in  a  thick  mesh  of  hyphae.  Petersen  identifies  this  as  also  the 
parasite  previously  reported  by  Muller  on  the  same  host.  The  latter 
found  (’68)  that  it  almost  exterminated  the  animal  from  a  lake  (Bogholm 
So)  in  Denmark. 

At  the  1909  meeting  of  the  North  Carolina  Academy  of  Science 
(reported  in  Science  30:  188,  August  6,  1909)  we  referred  to  our  plant 
as  a  new  species  of  Leptolegnia ,  but  we  now  think  it  to  be  nothing  else 
than  deBary’s  form. 

Our  observations  on  the  sporangia  agree  with  deBary’s  except  that 
in  old  cultures  the  sporangia  may  become  very  complex  from  the  ex¬ 
tension  of  a  single  sporangium  into  a  number  of  adjoining  branches. 
In  fig.  1  is  shown  such  a  sporangium  that  was  observed  before  and  during 
the  discharge.  All  the  spores  emerged  from  the  tip  of  one  of  the  branches 
(at  a  in  the  figure)  and  the  spores  at  the  tips  of  the  other  branches  had 
to  travel  all  the  way  down  these  and  out  at  a. 

DeBary  does  not  mention  the  shape  or  behavior  of  the  spores,  but 
we  found  them  to  exhibit  some  remarkable  peculiarities  (’09,  p.  263). 
In  nearly  all  cases  they  emerge  from  the  sporangium  much  drawn  out, 
as  long,  more  or  less  cylindrical  rods,  with  the  cilia  attached  to 
the  center  on  one  side.  As  soon  as  they  escape,  the  two  ends  of 
the  rod  begin  to  fold  backward,  away  from  the  cilia,  and  fuse  as  they 
go,  until  by  complete  fusion  they  lose  their  identity  and  form  a  pear- 
shaped  spore  with  the  cilia  near  the  tip,  and  the  long  axis  at  right  angles 
to  the  original  rod.  By  killing  the  spores  during  emergence  they  were 
caught  in  all  stages  of  this  transformation,  as  shown  in  fig.  5,  in  which 
a  shows  several  spores  that  were  killed  in  the  sporangium.  They  become 
more  elongated  as  they  pass  out  and  on  emergence  have  the  shape  shown 
in  b  or  c.  This  peculiar  habit  is  confirmed  by  Petersen  (To,  fig.  2). 
He  also  adds  that  the  spores  while  passing  out  of  the  sporangium  are 
linked  together  by  their  cilia  (see  p.  4  for  later  observations  by  Mr. 
Couch). 

Two,  three,  or  even  more  antheridia  to  the  oogonium  were  common 
in  our  material.  In  one  case  five  were  counted.  More  than  two  are  not 
mentioned  by  deBary.  The  antheridial  branches  are  generally  borne  as 
rather  short  offshoots  from  a  slender  main  branch  that  shows  a  marked 
tendency  to  twine  about  the  larger  female  branches  (figs.  2  and  3),  but 
they  may  terminate  a  long  branch.  They  are  always  of  diclinous  origin. 

The  antheridium  is  full  of  protoplasm  when  it  is  cut  off,  and  is 
empty  a  little  later;  and  the  amount  of  protoplasm  contained  in  it  is  so 
large  that  a  discharge  into  the  oogonium  seems  probable.  When  the 
empty  antheridium  is  pulled  from  the  oogonium  a  distinct  circular  open- 


i6o 


THE  SAPROLEGNIACEAE 


ing  can  be  seen  in  it  and  the  opening  in  the  original  membrane  on  the 
oogonium  can  be  easily  made  out  (fig.  4). 

The  oogonia  are  very  rarely  found.  We  had  cultivated  the  plant  for 
about  three  months  before  the  first  oogonia  appeared,  and  they  were 
matured  during  the  Christmas  recess.  They  have  been  produced  only 
two  or  three  times  since,  and  that  only  sparingly,  notwithstanding  our 
efforts  to  induce  sexual  reproduction  by  cultures  on  various  insects  and 
in  different  chemical  solutions.  The  results  of  some  of  these  experi¬ 
ments  are  as  follows: 

On  gnat  in  .05%  haemoglobin  solution  in  shallow  dish.  Growth  was  about  as  extensive 
as  in  water  but  there  was  a  much  more  profuse  branching,  especially  near  the  ends  of 
the  hyphae.  The  difference  was  easily  visible  to  the  naked  eye.  No  sexual  reproduc¬ 
tion. 

On  gnat  in  equal  parts  of  haemoglobin  .05%  and  Ca(N03)2  .2%.  About  twenty  oogonia, 
all  with  antheridia. 

Cultures  made  on  gnats  in  shallow  petri  dishes  gave  no  oogonia  in  any  of  the  following 
solutions  (equal  parts  haemoglobin  in  .05%  solution  and  chemicals  in  .2%  solution 
in  distilled  water  in  each  case) ; 

Haemoglobin  +  KNO3 
Haemoglobin  +  K6H3(P04)j 
Ca(N03)2 
KNO3 

K,H,(P04)* 

Cultures  on  gnats,  flies,  wasps,  mosquitoes  and  spiders  showed  no  noticeable  differences. 
Cultures  under  several  inches  of  water  were  unfavorable  for  the  formation  of  either  sexual 
or  asexual  reproductive  organs. 


APHANOMYCES  deBary,  i860,  p.  178. 


Hyphae  very  delicate,  long,  sparingly  branched.  Sporangia  formed 
from  unchanged  hyphae,  long  to  very  long,  not  proliferating  within 
old  ones  and  rarely  laterally  from  below.  Spores  borne  in  a  single  row, 
emerging  apically  in  elongated  form,  then  rounding  up  and  encysting 
in  a  clump  at  the  end  of  the  sporangium  as  in  Achlya ,  then  emerging  and 
swimming  again  as  in  that  genus.  Specialized  gemmae  absent.  Oo¬ 
gonia  terminal  on  short  or  long  branches,  smooth  or  warted,  wall  thin 
and  unpitted.  Antheridia  diclinous  or  androgynous,  not  a'ways  pres¬ 
ent.  Eggs  single,  not  filling  the  oogonium,  eccentric,  with  a  single 
large  fat  drop  in  the  protoplasm  near  one  side  or  with  a  lunate  disc 
of  oil  droplets  on  one  side.  Fertilization  has  been  proved  in  A.  laevis, 
which  see  for  details.  Spore  development  has  been  studied  by  deBary 
(’6o)  and  Rothert  (’03).  The  genus  shows  a  strong  tendency  to  para¬ 
sitism. 


Key  to  the  Species 

Oogonial  walls  smooth,  not  with  spines  or  warts;  eggs  16.5-26^  thick 


(  A.  laevis  (1) 

l  A.  helicoides  (p.  168) 


APHANOMYCES  161 

Oogonial  walls  uneven  or  tuberculate,  not  spiny;  eggs  1 3 — 1  8.5m  thick . A.  scaber  (2) 

Oogonial  walls  with  distinct  spines  or  papillae 

Oogonia  22— 33^  thick  (including  papillae) . j  A.  stellatus  (3) 

(A.  coniger  (p.  168) 

Oogonia  14-22^  thick . A.  parasitical) 

Oogonia  40— 50;t  thick,  the  wall  hyaline . A.  phycopkilus  (5) 

As  above,  but  oogonial  wall  brown . yt.  norvegicus  (p.  168) 


i.  Aphanomyces  laevis  deBary.  Jahrb.  f.  wiss.  Bot.  2:  179,  pi.  20, 

figs.  17-18.  i860. 

Plates  50  and  55 

Hyphae  saprophytic  or  rarely  parasitic  on  desmids  and  diatoms  (see 
below),  slender,  much  branched,  about  5-7. 5-4  thick.  .Sporangia  long  and 
of  the  same  size  as  the  hyphae,  often  extending  to  the  substratum.  Spores 
7.3-1 1 4  in  diameter  after  emerging,  most  about  9-104,  rod-shaped  in 
the  sporangium.  Oogonia  terminal  on  short  lateral  branches,  glob¬ 
ular  or  nearly  so,  with  smooth  thin  walls  without  pits,  18-334  in  diam¬ 
eter.  Eggs  single,  16.5-264  in  diameter,  mostly  about  19-224,  thick- 
walled,  eccentric,  with  one  very  large  fat  drop  enclosed  in  the  proto¬ 
plasm  and  very  near  the  surface  on  one  side.  Antheridial  branches  very 
abundant,  sometimes  twining  around  the  oogonial  branches  in  a  knot, 
androgynous  or  diclinous.  Antheridia  large,  abundant  on  all  oogonia 
and  extensively  wrapping  them  about;  antheridial  tubes  developed  and 
plainly  visible. 

This  species  has  been  recognized  three  times  in  Chapel  Hill  col¬ 
lections;  from  Lone  Pine  spring  (September),  and  from  New  Hope  Creek. 
It  has  probably  been  collected  at  other  times,  but  not  recognized  on 
account  of  its  failure  to  fruit.  It  was  found  by  Humphrey  at  Amherst, 
Massachusetts,  by  Pieters  at  Ann  Arbor,  Michigan  (Ann.  Rep.  Mich. 
Acad.  Sci.  8:  27.  1905),  and  we  have  obtained  it  mixed  with  A.  americana 
from  a  vial  of  water  with  a  little  trash  sent  us  in  June,  1920,  from  Woods 
Hole,  Massachusetts,  by  Mr.  George  M.  Gray,  Curator  of  the  Marine 
Biological  Laboratory.  It  is  easily  distinguished  by  its  smooth  oogonia 
from  all  except  the  smoothest  forms  of  A.  scaber ,  and  from  it  by  larger 
eggs,  and  large  and  numerous  antheridia.  For  other  illustrations  see 
Humphrey  (’92),  pi.  20,  figs.  1 05-107;  and  Petersen  (’10),  fig.  3c. 

In  a  collection  of  algae  and  trash  from  a  branch  near  Wilmington, 
N.  C.,  Dec.  30,  1921,  there  appeared  diatoms  and  chains  of  desmids  on 
which  grew  parasitically  a  species  of  Aphanomyces  which  proved  to  be 
A.  laevis  (pi.  50,  fig.  17).  The  threads,  which  were  3-6.64  thick,  en¬ 
tered  the  living  cells  of  the  algae  where  they  formed  a  branched  and 
more  or  less  contorted  and  undulated  complex  which  finally  destroyed 
the  contents  of  its  host.  All  reproductive  parts  were  borne  outside 
the  algae.  Sporangia  typical  for  the  genus;  spores  8.5-104  thick.  Oogonia 
22-324  thick;  walls  sinuous  but  without  warts  or  spines.  Eggs  single, 


THE  SAPROLEGN I  AC  EAE 


162 

14-29^  thick,  average  about  22[x,  eccentric  as  in  the  typical  form.  An- 
theridia  present  on  all  oogonia.  The  plant  was  cultivated  for  a  short 
time  on  ants  and  bits  of  boiled  corn  grain  but  grew  poorly  and  soon  died 
out.  It  may  be  best  to  consider  it  a  parasitic  variety  of  the  species. 

Our  typical  form  produces  oogonia  very  sparingly.  A  culture  was 
kept  going  in  the  laboratory  for  four  months,  on  different  media,  be¬ 
fore  any  oogonia  were  produced.  They  have  appeared  several  times: — 
on  ants  in  distilled  water,  on  mushroom  grubs  in  distilled  water,  and 
most  promptly  and  abundantly  on  the  protein  (horny)  part  of  corn 
endosperm  that  had  been  boiled  for  a  few  minutes.  In  each  case  they 
have  appeared  only  after  the  cultures  were  several  weeks  old.  The 
cultures  are  rather  hardy  and  will  last  for  some  time,  but  will  not  go 
through  the  summer  without  transfer. 

The  eggs  of  our  plant  run  smaller  than  deBary’s  measurements, 
which  are  27~33[x.  Some  of  the  spores  are  often  left  in  the  sporangia, 
and  sprout  there  into  hyphae  (pi.  55,  fig.  2). 

Dr.  Pieters  writes  (unpublished  notes)  that  “oogonia  developed  when 
a  mycelium  was  transferred  from  1%  peptone  to  0.05%  haemoglobin, 
July  24,  1914.  Antheridia  were  abundant  and  wrapped  about  the 
oogonia;  no  eggs  were  formed.” 

On  this  species  Kasanowsky  (Ti)  has  published  a  good  paper  show¬ 
ing  that  fertilization  occurs.  His  results  are  briefly  as  follows: 

The  young  oogonium  is  filled  with  plasma  and  contains  a  large 
number  of  nuclei  and  a  large  central  vacuole;  a  number  of  the  original 
nuclei  go  to  pieces,  others  divide  simultaneously  by  mytosis;  all  the 
nuclei  from  this  division  go  to  pieces  except  one  which  becomes  the 
egg-nucleus;  there  is  now  formed  a  dense  mass  with  radiating  strands 
called  the  coenocentrum,  comparable  to  the  similar  body  in  the  Pero- 
nosporaceae,  near  which  lies  the  egg  nucleus  which  increases  in  size. 
The  antheridia  contain  4-6  nuclei,  which  divide  mytotically  and  then 
degenerate  with  one  exception;  this  male  nucleus  is  then  discharged  into 
the  egg  through  a  fertilizing  tube,  along  with  the  protoplasm  of  the  an- 
theridium,  and  fuses  with  the  egg  nucleus;  fat  is  formed  in  small  particles 
which  fuse  to  form  larger  ones  which  finally  unite  to  form  a  single  large 
drop  with  a  distinct  membrane  and  probably  also  an  internal  ground¬ 
work  (stroma)  of  its  own.  The  ripe  egg  is  uninucleate,  with  the  large 
fat  drop  usually  in  the  center.  After  six  months  the  egg  sprouts  to  a 
tube  which  soon  branches. 

For  other  cytological  data  see  Dangeard  (’90),  p.  113,  pi.  6,  figs.  6-17. 


PLATE  55 


PLATE  55 
Aphanomyces  laevis 

Fig.  i.  Tip  of  empty  sporangium  showing  spore  cluster. 

Fig.  2.  Vegetative  threads  and  two  spores  sprouting  within  the  sporangium. 

Fig.  3.  Oogonium  with  diclinous  antheridia. 

Fig.  4.  Oogonium  with  diclinous  antheridia  and  visible  antheridial  tube. 

Fig.  5.  Oogonia,  the  one  on  left  with  both  diclinous  and  androgynous  antheridia. 

Fig.  6.  Oogonium  with  mature  egg  showing  structure. 

Fig.  7.  Oogonium  clasped  by  finger-like  antheridia;  two  antheridial  tubes  clearly  visible. 

All  figures  X  670. 


PLATE  55 


APHANOMYCES  LAEYIS. 


APHANOMYCES 


163 

2.  Aphanomyces  scaber  deBary.  Jahrb.  f.  wiss.  Bot.  2:  178,  pi.  20, 

figs.  14-16.  i860. 

Plate  50  and  56 

Hyphae  delicate,  branching,  about  5-7. 5;j.  thick,  rarely  as  small  as  2.5;;.. 
Sporangia  like  the  hyphae,  of  indefinite  length.  Spores  on  encysting 
about  9.5^  thick;  narrow  and  elongated  in  the  sporangium.  Oogonia 
terminal  on  short  or  moderately  long  branches,  very  small,  15-23.7:0. 
in  diameter,  averaging  about  21.5(0.  in  No.  1  of  January  6,  1914,  surface 
uneven  or  varying  to  tuberculate,  but  projections  never  so  prominent 
as  in  A.  stellatus ;  wall  thin,  not  pitted.  Eggs  single,  13-18.5(0.  in  diam¬ 
eter,  averaging  about  15.5(0.  in  No.  1  of  January  6,  1914,  about  13.3(0.  in 
No.  8  of  November  15,  1913,  eccentric,  a  single  large  oil  drop  near  one 
side  (our  figs.  8-10  are  not  oriented  to  show  the  full  eccentricity),  proto¬ 
plasm  small  in  quantity  and  light  in  color,  wall  rather  thick.  Anther- 
idia  not  seen  in  our  form;  present  on  most  of  the  oogonia,  according 
to  Fischer;  not  on  all  oogonia,  according  to  Humphrey. 

Not  rare  at  Chapel  Hill;  occurring  in  brooks  and  springs,  as  brook 
below  Howell’s  spring,  brook  behind  athletic  field,  etc.  Humphrey  has 
reported  it  from  Massachusetts,  where  he  also  found  a  more  spiny  form. 
For  other  illustrations  see  deBary  (’8i),  pi.  6,  figs.  30-36;  and  Hum¬ 
phrey  (’92),  pi.  20,  figs.  108— III. 

This  species  does  not  fruit  so  easily  or  abundantly  as  A.  stellatus, 
but  is  easily  distinguished  from  it,  when  fruiting  does  occur,  by  the 
small  oogonia  and  eggs  and  by  the  much  less  papillate  oogonia.  From 
A.  laevis  it  differs  in  smaller  eggs,  rougher  and  smaller  oogonia  and  ab¬ 
sence  of  antheridia  from  all  (in  our  form)  or  some  of  the  oogonia. 

On  corn  meal  and  egg  yolk  agar  a  strong  growth  occurs,  but  reproduction  is  absent. 

On  mushroom  grubs  in  distilled  water  sporangia  are  produced  but  oogonia  are  rare. 

3.  Aphanomyces  stellatus  deBary.  Jahrb.  f.  wiss.  Bot.  2:  178,  pi.  19, 

figs.  1-13.  i860. 

Plate  56 

Hyphae  straight,  delicate,  little  branched,  about  5.5-6.5'j.  in  diam¬ 
eter,  springing  abundantly  from  the  substratum,  the  tips  rounded.  Spor¬ 
angia  produced  from  the  unchanged  hyphae,  very  long,  usually  reaching 
to  the  substratum.  Spores  when  in  the  sporangium  irregularly  rod¬ 
shaped  with  uneven  ends,  on  escape  becoming  rounded  and  encysting 
in  an  irregular  group  at  the  mouth  of  the  sporangium,  diameter  8-8. 5;j. 
(at  times  a  few  larger  double  ones  ii-I2(j.  in  diameter  mixed  with  the 
others),  emerging  and  swimming  actively  with  the  usual  form,  the  large 
cysts  giving  rise  to  two  spores  of  normal  size,  according  to  deBary, 
and  confirmed  by  us.  Oogonia  subspherical,  borne  on  rather  long  or 
short  lateral  branches,  normally  covered  more  or  less  densely  with  con¬ 
spicuous  blunt  papillae  up  to  5.5’j.  long,  diameter  of  the  oogonia,  including 
the  papillae,  about  22-330.;  walls  rather  thin,  unpitted,  cavity  extending 


164 


THE  SAPROLEGNIACEAE 


into  the  papillae.  Eggs  about  16-264  thick,  most  about  18.54,  single 
(rarely  two — deBary),  contents  eccentric  when  fully  mature,  with  an 
inconspicuous  lunate  series  of  droplets  on  one  side  in  optical  section. 
Antheridial  branches  androgynous  or  also  from  neighboring  threads, 
often  branched.  Antheridia  short-tuberous,  large,  present  on  all  or  nearly 
all  oogonia.  Fertilization  uncertain. 

The  species  is  typically  saprophytic,  but  we  have  found  it  also  para¬ 
sitic  on  Achlya  (see  below).  It  is  very  plentiful  around  Chapel  Hill  in 
springs,  brooks,  and  creeks,  occurring  in  about  25%  of  all  Chapel  Hill 
collections.  It  has  not  been  reported  heretofore  from  America,  but  is 
probably  widespread.  For  other  illustrations  see  Sorokine  (’76),  pi.  7; 
Massee  (’91),  pi.  6,  figs.  105-108.  For  cytological  detail  in  an  unnamed  spe¬ 
cies  which  maybe  this,  see  Dangeard  (’90),  p.  117,  pi.  6,  figs.  18-23.  It  is 
easily  distinguished  from  A .  laevis  by  its  conspicuously  papillate  oogonia  and 
by  the  numerous  antheridia  of  mostly  diclinous  origin.  From  A.  scaber 
it  differs  in  the  decidedly  larger  eggs  and  oogonia.  Moreover,  the  walls 
of  A.  scaber ,  while  uneven,  are  much  less  papillate.  Oogonia  are  abun¬ 
dantly  produced  in  all  fairly  normal  condit’ons,  as  on  animal  and  plant 
bodies,  nutrient  agar,  etc.,  in  this  respect  differing  from  A.  laevis 
and  A.  scaber ,  where  fruiting  is  rare.  The  antheridia  are  formed  early 
and  reach  the  oogonia  while  the  latter  are  still  young  and  without  their 
papillae.  We  have  not  observed  antheridial  tubes,  but  they  would  be 
difficult  to  see  if  present,  and  may  be  formed.  The  variation  in  the  number 
of  antheridial  branches  is  a  marked  characteristic.  In  a  collection  from 
New  Hope  Creek  no  antheridia  appeared  in  at  least  half  a  dozen  cultures  on 
grubs  in  distilled  water,  but  appeared  abundantly  on  at  least  90%  of  the 
oogonia  when  grown  on  a  lump  of  corn  meal  agar  with  grubs  added  in  dis¬ 
tilled  water.  On  a  piece  of  pea  root  growth  was  fairly  vigorous,  but  even 
more  slender  than  on  grubs;  much  branched;  oogonia  abundant,  a  good 
many  with  antheridia.  On  solid  corn  meal  agar  growth  was  vigorous, 
with  oogonia  in  fair  amount  and  antheridia  on  many  of  them. 

Abnormalities  of  the  usual  nature  occur.  Spores  may  be  left  in 
the  sporangia,  particularly  a  few  of  the  last  ones,  and  may  sprout  there 
through  the  wall  to  form  a  hypha  or,  according  to  Sorokine,  the  retained 
spores  may  form  short  tubes  and  liberate  spores  as  in  Dictyuchus. 

We  have  found  several  times  in  Chapel  Hill  a  form  of  this  species 
differing  from  the  typical  only  in  being  parasitic  on  species  of  Achlya. 
The  plentiful  oogonia  are  borne  both  inside  and  outside  the  Achlya  threads. 

With  only  the  oogonia  at  hand,  this  species  could  easily  be  confused 
with  Saprolegnia  asterophora.  In  the  latter,  however,  both  oogonia  and 
eggs  average  larger,  antheridia  are  often  absent,  and  the  sporangia,  of 
course,  quite  different. 


PLATE  56 


PLATE  56 

Aphanomyces  stellatus 

Fig.  i.  Tip  of  sporangium,  showing  spore  cluster  with  a  good  many  empty  cysts  and  two 
spores  which  remainded  in  the  sporangium. 

Fig.  2.  Young  oogonia,  one  showing  the  beginnings  of  the  papillae. 

Fig.  3.  Young  oogonium  without  papillae. 

Fig.  4.  Oogonium  before  formation  of  egg. 

Fig.  5.  Oogonium  with  oval-shaped  egg. 

Fig.  6.  Oogonium  without  antheridium. 

Fig.  7.  Oogonium  with  papillae  and  single  egg. 

All  figures  X  503. 

Aphanomyces  scaber 

Fig.  8.  Oogonium  with  ripe  egg  and  attached  hypha. 

Figs.  9  and  10.  Oogonia  with  ripe  eggs. 

All  figures  X  810. 


PLATE  56 


APHANOMYCES  STELLATUS  [ABOVE]. 
APHANOMYCES  SCABER  [LOWER  THREE]. 


APHANOMYCES 


165 

DeBary’s  measurements  for  the  eggs  compared  with  ours  are  rather 
large,  his  being  27-359.  in  diameter.  He  remarks  (’6o,  p.  173)  that  in 
this  species  the  spore  ball  at  the  sporangium  mouth  may  be  two 
spores  thick  around  the  central  cavity  and  that  the  spores  at  the  moment 
of  emergence  are  held  together  very  weakly  and  may  be  separated  from 
each  other  and  from  the  sporangium  mouth  by  a  slight  current  of  water. 

All  the  following  cultures  were  made  from  No.  10  of  January  30, 
1913: 

In  equal  parts  maltose  5%  +  peptone  .01%.  Growth  only  about  K  inch  in  diameter. 
No  reproductive  bodies. 

On  white  of  egg  in  distilled  water.  Good  growth  and  a  good  many  scattering  oogonia  with 
antheridia. 

On  ant  in  distilled  water.  Good  growth.  An  immense  number  of  good  oogonia  with 
antheridia.  Also  sporangia. 

On  mushroom  grub  in  distilled  water.  Good  growth.  Abundant  oogonia. 

On  corn  meal  agar.  Growth  strong,  covering  dish.  Oogonia  quite  scattering,  but  many 
in  the  dish,  all  with  antheridia  and  good  eggs  and  with  tubercles  of  about  usual  size. 
On  corn  meal  egg  yolk  agar.  Growth  fine  and  strong.  An  immense  number  of  fine  oogonia, 
all  with  antheridia  and  good  eggs. 

Experiments  to  test  best  method  of  preserving  live  cultures: 

Culture  put  in  vial  on  corn  meal  agar  on  March  18,  1913.  When  tested  on  December  1, 
1913,  it  was  found  to  be  dead. 

Culture  on  corn  meal  agar  put  in  vial  of  water  which  was  closed  with  a  plug  of  cotton  and 
put  in  a  dark  place  in  May,  1913.  When  tested  in  December,  1913,  it  was  found  to 
be  alive.  All  eggs  seemed  to  be  dead. 

Culture  put  in  aquarium  jar  with  algae  in  laboratory.  When  tested  on  September  18, 
1917,  no  growth  appeared. 

4.  Aphanomyces  parasitic^~n.  sp. 

Plate  57 

Hyphae  parasitic  on  vegetative  threads,  young  sporangia  and  young 
oogonia  of  species  of  Achlya  (A.  flagellata,  A.  Orion,  sterile  Achlya,  No. 
1  of  August  13,  1921),  not  attacking  the  gemmae  or  eggs.  Vegetative 
hyphae  endophytic  at  first,  traversing  the  Achlya  threads  from  base  to 
tip,  and  growing  out  through  the  walls  of  the  Achlya  only  after  exhausting 
the  threads.  Threads  of  parasite  3-5.59.  thick,  most  about  49.;  straight 
and  even  at  first,  becoming  somewhat  swollen  in  places  and  distorted 
with  age.  Sporangia  usually  formed  outside  the  host  and  emptying 
normally  for  the  genus,  the  spores  encysting  at  the  sporangial  tip.  If 
formed  within  the  host,  which  is  not  rarely  the  case,  the  spores  do  not 
emerge,  but  encyst  within  the  sporangium.  Spores  7.4-1 1 9.  thick,  di- 
planetic.  Oogonia  usually  borne  within  the  Achlya  thread,  not  rarely 
without  it,  on  short,  lateral,  inconspicuous  branches,  14-229.  thick,  not 
including  spines;  wall  warted  to  strongly  spiny,  spines  rarely  up  to  39. 
long.  Eggs  single,  eccentric,  filling  the  oogonium,  12. 8-2 1.79.  thick.  An- 
theridial  branches  of  diclinous  origin,  usually  long;  antheridia  single, 
irregularly  oval,  n  x  149.;  applied  to  the  base  of  the  oogonium  and  often 


THE  SAPROLEGNIACEAE 


1 66 

obscuring  the  oogonial  stalk;  the  contents  emptying  completely  into  the 
oogonium. 

Collected  only  once  and  then  in  a  little  wet  weather  branch  on  the 
north  border  of  Strowd ’s  low-ground  meadows  (No.  i  of  March  8,  1922). 

In  some  respects  the  present  species  resembles  A.  scaber.  The  size  of 
the  oogonia  in  the  two  plants  is  about  the  same.  In  A.  scaber  the  oogonial 
walls  may  be  set  with  numerous  short  warts  or  prominences,  or  may  be 
merely  irregularly  roughened,  while  in  the  former  the  oogonial  walls  may 
be  covered  with  blunt  spines  or  with  long,  conspicuous,  sharp  spines,  the 
walls  approaching  most  often  the  latter  condition.  Thus  the  most  uneven 
type  of  oogonia  in  A.  scaber  resembles  the  least  spiny  type  of  A.  parasitic $1 
The  two  plants  are  readily  distinguished  by  their  antheridia:  in  the  Chapel 
Hill  form  of  A.  scaber  the  antheridia  are  absent;  in  the  Massachusetts  form 
(Humphrey)  the  antheridial  branches  are  of  androgynous  or  diclinous 
origin,  the  antheridia  are  small  and  are  not  present  on  all  the  oogonia. 
In  A.  parasitica  the  antheridial  branches  are  of  diclinous  origin,  the  an¬ 
theridia  are  large  and  are  present  on  all  oogonia. 

The  present  form  could  hardly  be  confused  with  any  other  described 
species  of  Aphanomyces.  In  A.  stellatus  the  larger  oogonia  are  covered 
with  thick,  blunt  papillae  and  there  are  several,  usually  androgynous, 
antheridia  on  each  oogonium.  In  A.  laevis  spines  are  totally  absent  from 
the  oogonial  wall  but  quite  often  the  wall  is  angular.  In  A.  phycophilus , 
a  form  parasitic  upon  algae,  the  oogonia  have  small  sharp  spines,  but 
the  oogonia  and  eggs  are  much  larger.  Of  the  three  species  added  since 
deBary  established  the  genus  Aphanomyces,  all  are  either  insufficiently 
known  or  of  doubtful  validity.  In  A.  coniger  Petersen  (doubtful  species) 
the  oogonia  are  30-40^  thick,  and  in  A.  norvegicus  the  oogonia  are  borne 
outside  the  host  and  have  brown  walls. 

In  its  parasitic  habit  this  plant  is  exacting.  Several  Achlyas  have 
been  successfully  inoculated  with  the  parasite,  but  the  plant  refuses  to 
grow  on  A  planes  Treleaseanus  or  Isoachlya  unispora.  Four  attempts 
have  been  made  to  grow  single  spores  from  the  parasite  on  corn  meal  agar, 
but  the  spores  in  each  case  refused  to  sprout.  Epiphytic  threads  of  the 
parasite  have  been  cut  out  and  placed  on  corn  meal  agar,  termite  ants 
and  pieces  of  boiled  corn  grain,  but  no  growth  took  place.  Single 
Achlya  threads,  apparently  exhausted  by  the  parasite,  were  placed  on 
corn  meal  agar.  The  Achlya  threads  sprouted  and  grew  but  no  Aphan¬ 
omyces  threads  were  recognizable  until  after  the  Achlya  threads  had 
attained  a  length  of  about  two  centimeters,  and  then  the  threads  of  the 
parasite  were  seen  within  the  Achlya  threads.  All  efforts  so  far  to  grow 
the  plant  apart  from  an  Achlya  have  been  unsuccessful. 


PLATE  57 


PLATE  57 


Aphanomyces  parasitic/*.  n.  sp. 

Fig.  I.  Threads  of  the  parasite  growing  out  through  the  walls  of  an  Achlya  hypha  after 
completely  filling  it.  X  122. 

Fig.  2.  Oogonia;  most  within,  one  outside  the  Achlya  threads.  X  122. 

Fig.  3.  Sporangia;  formed  outside  the  Achlya.  X  278. 

Fig.  4.  Young  threads  of  the  parasite  growing  through  an  Achlya  thread.  X  1012. 

Fig.  5.  Hyphae  of  the  parasite  attacking  an  actively  growing  thread  of  Achlya.  A  vacuole 
appears  just  in  front  of  the  growing  tip  of  a  parasite  thread  which  has  been 
turned  back  thereby.  X  1012. 

Fig.  6.  A  young  oogonium  and  antheridium.  X  810. 

Fig.  7.  Surface  view  of  an  cogonium  inside  an  Achlya  thread,  showing  large,  sharp  spines. 

X  1012. 

Fig.  8.  Oogonia  and  antheridia  within  an  Achlya  oogonium.  X  503. 

Fig.  9.  Oogonia  and  antheridia  within  an  Achlya  hypha.  X  810. 

Fig.  10.  Oogonium  with  ripe  egg,  showing  eccentric  structure;  antheridium  attached. 

X  1012. 

Fig.  11.  Oogonium  with  ripe  egg  shown  at  an  angle  which  obscures  the  eccentric  structure: 
antheridium  attached.  X  1012. 

Fig.  12.  Oogonia  and  antheridia.  x  503- 

Fig.  13.  Oogonia  and  antheridia.  X  1012. 

All  oogonia  shown,  except  one  in  Fig.  12,  were  formed  inside  the  host. 


PLATE  57 


APHANOMYCES  PARASITIC^. 


APHANOMYCES 


167 


It  is  not  very  surprising  to  find  another  parasitic  species  belonging 
to  this  genus,  for  all  the  previously  known  forms  in  it  have  shown  para¬ 
sitic  habits  at  times.  As  mentioned  above  we  have  often  observed  A. 
stellatus  growing  in  Achlya  threads,  and  have  found  Aphanomyces  laevis 
growing  on  live  desmids  and  diatoms. 

5.  Aphanomyces  phycophilus  deBary.  Jahrb.  f.  wiss.  Bot.  2:  179,  pi. 

20,  figs.  19-24.  i860. 

This  interesting  parasite  has  been  reported  from  America  by  Kauffman 
from  Michigan  (Ann.  Rep.  Mich.  Acad.  Sci.  17:195.  I9I5)  and  by  Weather- 
wax  (’14)  from  Indiana.  In  unpublished  notes,  kindly  submitted  to 
us  by  Dr.  Pieters,  he  says  it  was  determined  as  such  from  an  oogonium 
found  in  Spirogyra  collected  at  Ann  Arbor  in  1913,  but  no  culture  was  made, 
nor  was  it  found  again. 

As  deBary’s  original  treatment  is  long  we  adapt  the  following  in  great 
part  from  the  more  condensed  description  by  Fischer  (Rabenhorst’s 
Krypt.  Flora  1,  part  4:  360.  1892): 

Threads  stouter  than  in  other  species,  8-15^.  thick,  creeping  longi¬ 
tudinally  through  the  host  cells  for  some  distance  by  penetrating  the 
cross  walls;  other  threads  extend  outside  the  host  and  these  bear  the 
reproductive  organs.  Sporangia  threadlike,  but  not  further  described; 
spore  formation  not  observed.  Oogonia  on  the  ends  of  short  threads 
outside  of  the  host,  very  rarely  inside  the  cells;  spherical,  40-50^  thick, 
the  hyaline,  unpitted  wall  thickly  set  with  short,  rather  sharp  spines. 
Eggs  spherical,  single;  sprouting  not  observed.  Antheridia  1-3  on  each 
oogonium,  short,  club-shaped,  with  their  tips  against  the  oogonia,  borne 
on  the  ends  of  short  branches  which  arise  from  nearby  threads. 

An  obligate  parasite  on  Spirogyra  and  Zygnema  and  not  to  be  cul¬ 
tivated  on  insects,  etc. 

Although  deBary  did  not  observe  the  asexual  reproduction  there 
is  little  or  no  doubt  that  he  was  right  in  referring  the  plant  to  Aphano¬ 
myces.  In  a  short  article  by  Weatherwax  (’14,  p.  109),  he  gives  the 
diameter  of  the  egg  as  about  36(0.,  its  wall  3-4^  thick;  the  spines  of  the 
oogonia  5-8^  long.  His  plant  attacked  but  one  species  of  Spirogyra 
(S.  dubia),  ignoring  other  species  in  the  same  culture.  His  figures  1-6 
show  oogonia  and  threads;  he  did  not  find  sporangia. 

A  problematic  plant  but  almost  certainly  a  species  of  Aphanomyces 
is  Achlyogeton  solatium  Cornu  (’70,  p.  298).  It  is  parasitic  in  Oedo- 
gonium,  and  may  be  the  present  species,  though  more  apt  to  be  dis¬ 
tinct,  as  Fischer  thinks.  From  Fischer  we  take  the  following  con¬ 
densed  description  (’92,  p.  361): 

“Mycelium  more  or  less  branched,  boring  through  the  cross  walls 
of  the  host.  Sporangia  cut  off  by  cross  walls,  not  different  from  the 
threads,  emptying  by  a  long  emission  tube  which  runs  to  the  exterior; 


THE  SAPROLEGNIACEAE 


168 

spores  3-12  in  a  sporangium,  encysting  themselves  at  the  mouth  of  the 
sporangium;  oogonia  formed  inside  the  host  cells,  irregularly  cylindrical 
with  perpendicular  projections;  eggs  one  or  few;  antheridia  not  ob¬ 
served.” 


EUROPEAN  SPECIES  NOT  FOUND  IN  AMERICA 

Aphanomyces  coniger  Petersen.  Bot.  Tidsskr.  29:387.  1909.  Also  in 

Ann.  Myc.  8:  525,  fig.  3b  and  f.  1910. 

This  species,  rather  recently  described,  has  not  yet  been  found  in 
America.  The  following  is  adapted  from  the  original: 

Hyphae  5-154  thick;  oogonia  without  pits,  the  wall  brown  and 
with  great  rounded  protuberances,  which  are  more  or  less  conical  in 
shape;  diameter  of  oogonia  with  processes  30-404,  processes  alone  about 
84;  eggs  single,  i6-3o(?)[x  thick;*  antheridial  branches  in  part  androg¬ 
ynous,  in  part  diclinous  from  a  distance,  in  this  respect  resembling 
A.  laevis.  Resembling  A.  stellatus  in  the  oogonial  protuberances,  but 
not  to  be  referred  to  that  species.  Observed  only  once  on  the  tegument 
of  a  nymph  of  one  of  the  Phryganeae. 

The  zoospores  were  not  seen  to  emerge  and  Petersen  is  in  doubt 
in  referring  it  to  Aphanomyces.  It  seems  very  likely  that  it  is  an 
Aphanomyces ,  however,  as  remarked  by  Minden.  Granting  the  species 
to  be  in  this  genus,  it  is  not  obvious  to  me  that  it  differs  from  A.  stel¬ 
latus.  The  slight  differences  in  the  measurements  given  do  not  seem 
important,  and  no  other  discrepancies  appear. 

Aphanomyces  norvegicus  Wille.  Videnskab.  Skrifter.  Ser.  I,  Math.  Na- 

turw.  Klasse  No.  3,  p.  9,  figs.  14-27.  1899. 

This  species,  reported  only  from  Norway,  is,  like  A.  phycophilus , 
parasitic  on  the  Conjugatae  ( Spirogyra ,  Zygnema,  and  Mougeotia).  It 
differs  from  that  species  in  having  the  mycelium  wound  outside  the  algal 
threads  as  well  as  running  inside,  and  in  the  brown  (not  hyaline)  wall  of  the 
oogonium,  which  is  strongly  papillate.  The  oogonia  are  nearly  always 
borne  outside  the  host.  For  full  description  see  Minden  (’12,  p.  561). 
This  also  has  not  been  found  in  America,  and  in  our  opinion  further  study 
is  required  to  establish  it  as  certainly  distinct  from  A.  phycophilus.  The 
size  of  the  eggs  is  not  given  by  Wille. 

Aphanomyces  helicoides  Minden.  Krypt.  FI.  Mark  B.  5:  559.  1912. 

It  is  very  probable  that  this  is  not  different  from  A.  laevis  as  there 
is  a  strong  tendency  for  the  antheridial  branches  to  coil  in  our  Chapel 
Hill  form  of  that  species. 

*The  original  says  16-70^,  an  evident  error.  We  guess  at  30^  as  that  would  be  about 
right  from  the  size  of  the  oogonia. 


LEPTOMITACEAE 


169 


The  following  is  translated  from  the  original  (there  are  no  figures) : 

“Mycelium  and  sporangia  as  in  A.  laevis.  Oogonia  terminal,  rarely 
intercalary,  mostly  on  very  short  side  branches,  more  or  less  spherical, 
with  smooth,  moderately  thick  membrane;  without  pits;  23-38:0.  in 
diameter.  Antheridia  large,  often  long,  cylindrical,  usually  several  on 
an  oogonium  and  spirally  wrapping  them  around,  as  well  as  their  stalks, 
later  with  brown,  thickened  membrane,  and  lying  isolated  on  the  oogonia 
on  account  of  the  disappearance  of  their  stalks.  The  antheridial  threads 
arise  in  part  from  special  hyphae,  in  part  from  those  that  bear  oogonia. 
They  often  wind  themselves  thickly  about  each  other,  and  also  about 
other  threads,  even  around  those  that  do  not  bear  oogonia,  so  that  they 
may  make  a  thick  tangle  in  the  neighborhood  of  the  oogonia.  Eggs 
single,  spherical,  23-27^  thick,  with  large  fat  drops,  which  are  mostly 
on  one  side,  but  not  always  visible. 

“Found  near  Hamburg,  and  cultivated  on  ant  eggs. 

“The  sex  organs  are  developed  very  richly  with  the  sporangia  in 
conditions  where  other  Aphanomyces  species  do  not  develop  them. 
This  species  is  nearly  related  to  A.  laevis,  and  is  possibly  only  a  variety 
of  it.  However,  the  long  antheridial  branches,  which  often  wind  about 
the  hyphae,  and  the  often  snake-like  twisting  of  the  antheridia,  would 
seem  to  justify  the  establishment  of  a  new  species.” 


LEPTOMITACEAE 

Filaments  constricted  at  intervals  to  form  a  series  of  long  or  short 
segments;  often  showing  conspicuous  particles  of  material,  supposed  to 
be  cellulin,  which  may  entirely  fill  the  constriction.  Oogonia  if  present 
containing  a  single  egg,  which  is  surrounded  by  periplasm  except  in 
Apodachlya. 

The  fungi  composing  this  family  were  included  in  the  Saproleg- 
niaceae  until  Schroeter  established  the  family  in  1893.  Thaxter  (1896, 
p.  324)  has  called  attention  to  the  fact  that  they  are  more  related  to 
the  Pythiaceae  than  to  the  Saprolegniaceae. 

Of  the  species  now  included  in  the  family  we  have  studied  only  Lep- 
tomitus  lacteus,  Apodachlya  brachynema  and  Sapromyces  Reinschii ,  the 
former  of  wide  distribution  and  frequent  appearance  in  collections.  For 
convenience  we  give  below  a  tabular  view  of  the  genera  and  species  now 
recognized  in  the  Leptomitaceae. 

Gonapodya  siliquaeformis  (Reinsch)  Thaxter  (1895a).  See  also  Petersen  (To,  fig.  11). 
Gonapodya  polymorpha  Thaxter  (1895a).  See  also  Petersen  (To,  figs.  12-14). 

Leptomitus  lacteus  Ag.  (1824).  See  below. 

Apodachlya  pyrifera  Zopf.  (1888). 

Apodachlya  pyrifera  var.  macrosporangia  Tiesenhausen  (1912,  p.  295,  fig.  19). 


i;o 


THE  SAPROLEGNIACEAE 


Apodaclilya  brachynerra  (Hildb.)  Prings.  (1883).  See  below. 

Apodnchlya  brachynema  var.  major  Tiesenhausen  (1912,  p.  296,  fig.  20). 

Apodachlya  completa  Humphrey  (1893).  The  position  of  this  plant  is  quite  uncertain 
until  further  observations  can  be  made. 

Rliipidium  inter r upturn  Cornu  (1871). 

Rhipidium  continuum  Cornu  (1871).  See  also  Petersen  (’10,  fig.  4a  and  e). 

Rliipidium  americanum  Thaxter  (1896). 

Araiospora  pulchra  Thaxter  (1896). 

Araiospora  spinosa  (Cornu)  Thaxter  (1896). 

Sapromyces*  Reinschii  (Schroeter)  Fritsch  (1893).  See  below. 

Sapromyces  androgynus  Thaxter  (1896). 

Sapromyces  elongatus  (Cornu)  Thaxter  (1896). 


LEPTOMITUS  Agardh,  1824,  p.  47. 

Hyphae  delicate,  sparingly  branched  apically  and  soon  appearing 
dichotomous,  constricted  at  intervals  into  distinct  segments  with  a  con¬ 
spicuous  cellulin  plug  separating  them  (thus  differing  essentially  from 
the  Saprolegniaceae).  Sporangia  apical  and  then  in  rows  in  basipetal 
succession.  Spores  in  a  single  row  (or  nearly  so),  escaping  as  in  Sapro- 
legnia  and  of  the  same  habit  and  structure  (diplanetic),  biciliate.  Oo- 
gonia  and  antheridia  never  observed.  There  is  but  one  species  now  rec¬ 
ognized  as  good,  though  many  have  been  described. 

Leptomitus  lacteus  (Roth)  Agardh.  Systema  Algarum,  p.  47.  1824. 

Apodya  lactea  Cornu.  Ann.  Sci.  Nat.  Bot.  15:  5.  1872. 

Plate  58 

Characters  of  the  genus.  The  species  may  be  found  at  almost  any  time 
by  taking  slime  from  sewers  or  streams  contaminated  with  sewage.  In  such 
places  it  is  often  so  abundant  as  to  whiten  all  surfaces  and  objects  in  the 
water,  as  we  have  often  seen  in  Chapel  Hill  and  in  Baltimore,  Maryland. 
Huxley  (Quart.  Jour.  Mic.  Sci.  22 :  331.  1882),  quoting  from  Geoppert,  says 
that  “refuse  from  a  factory  for  making  alcohol  from  turnips  near  Schweid- 
nitz  in  Silesia,  poured  into  the  river  Westritz,  caused  such  a  prodigious 
growth  of  Leptomitus  that  the  fungus  covered  some  10,000  sq.  ft.  of  the 
bottom  with  a  thick  white  layer,  compared  (sic)  to  a  sheep’s  fleece,  choked 
up  the  pipes,  and  rendered  the  water  of  the  town  undrinkable.”  See 
also  Bot.  Zeit.  2:  163.  1853. 

Observations  by  Radais  (’98,  p.  147)  on  the  behavior  of  the  cellulin 
granules  are  of  sufficient  interest  to  translate.  He  says: 

*  Syn.  Naegelia  Reinsch  (1878):  Naegeliella  Schroeter  (1893).  See  Fritsch  (1893, 
p.  420).  Tiesenhausen  (’12)  also  reports  this  (p.  298,  figs.  21,  22). 


PLATE  58 


PLATE  58 
Leptomitus  lacteus 

Figs,  i,  2,  3.  Resting  sporangia.  1  X  250;  2  and  3  X  670. 

Fig.  4.  Showing  method  of  branching  and  constriction.  X  670. 

Fig.  5.  (a)  Empty  sporangium;  (b)  spores  in  a  sporangium.  X  670. 
Fig.  6.  Spores  and  empty  cysts.  X  670. 

Fig.  7.  An  old  hvpha  with  a  conspicuous  cellulin  plug.  X  670. 

Fig.  8.  Characteristic  appearance  of  the  particles  near  a  constriction. 


X  670. 


PLATE  58 


LEPTOMITUS  LACTEUS 


LEPTOMITUS 


171 


“These  spheroids  have  been  earlier  studied  by  Pringsheim  from  a 
morphological  point  of  view.  Their  number  in  each  segment  is  variable, 
one  at  least  always  appears  in  a  young  segment;  later  the  number  may 
be  increased.  Sometimes  one  may  notice  them  in  some  place  in  the  body 
of  the  segment,  sometimes  they  are  localized  in  the  constriction  which 
they  obstruct.  This  last  situation  is  always  noticeable  when  the  thread 
has  been  broken  at  the  center  of  the  constriction  which  they  obstruct. 
If  the  rupture  is  recent  the  cellulose  granule  is  simply  applied  at  the 
opening  and  obstructs  it  by  simple  contact;  the  protoplasmic  contents 
are  thus  motionless  in  the  hypha.  If  the  wound  is  older  an  adhesion 
appears  between  the  granules  and  the  cellulose  wall,  of  such  a  nature 
that  in  the  same  kind  of  wounds  of  different  ages  one  can  see  all  the 
intermediate  stages  between  the  application  pure  and  simple  of  the  un¬ 
changed  cellulose  spheroid,  which  closes  the  conical  tube  like  a  valve, 
and  the  adhesion  with  change  of  form  of  this  spheroid,  which  soon  forms 
a  new  tip  of  the  hypha  which  may  now  continue  its  apical  growth. 

“This  role  of  stopcock  by  immediate  application  and  ultimate  ad¬ 
hesion  is  carried  out  by  the  cellular  granules  not  only  opposite  the  opening 
of  the  apex,  produced  by  accidental  ruptures  of  the  filaments,  but  also 
opposite  all  the  lateral  perforations  which  one  can  make  intentionally 
with  a  needle. 

“As  to  the  manner  in  which  the  spheroid  fulfills  its  function,  I  have 
been  able  to  observe  directly  beneath  the  microscope  the  rapid  move¬ 
ment  of  the  cellulose  granule  as  far  as  the  opening  intentionally  made  in 
the  thread.  It  does  not  seem  to  me  that  this  change  of  position  is  the 
result  of  an  intrinsic  motion.  I  consider  it  rather  a  mechanical  force 
due  to  the  protoplasmic  current  which  determines  the  sudden  diminu¬ 
tion  of  the  turgescence  at  the  moment  of  the  opening  of  the  tube. 

“If  the  preceding  facts  seem  to  me  to  justify  the  explanation  which 
I  am  giving  it  does  not  follow,  however,  that  the  function  of  building  up 
the  membrane  of  the  hyphae  is  the  only  one  which  can  be  attributed 
to  the  cellulose  grains.  Perhaps  this  form  of  carbohydrate  inside  of  the 
cell  is  available  for  some  other  use.  Whatever  it  may  be,  the  special 
function  which  I  have  been  able  to  observe  is  not  sufficient  to  explain 
the  larger  number  of  spheroids  in  the  older  segments  of  the  plant.” 

The  appearance  of  a  culture  is  more  delicate  and  flaccid  than  that  of 
a  Saprolegnia ,  the  threads  about  8.5-16^  in  thickness,  and  the  growth  is 
less  vigorous  and  certain  under  laboratory  conditions.  We  have  found 
slightly  boiled  cow  peas  the  best  medium  on  which  to  cultivate  it. 
The  sparse  branching  is  all  done  near  the  tips  and  soon  presents  a 
dichotomous  appearance.  The  sporangia  are  sparingly  formed  from 
slightly  enlarged  segments,  at  first  apical  then  often  in  rows,  opening 


I  72 


THE  SA  P  ROLEG  X I  AC  E  A  E 


at  the  tip  or  on  the  side  to  discharge  the  actively  motile,  biciliate  spores 
which  are  formed  in  a  single  row,  or  imperfectly  in  two  rows,  and  are 
about  io. 5-1 1  [x  in  diameter.  They  are  diplanetic,  a  fact  hitherto  un¬ 
certain  on  account  of  conflicting  reports.  Pringsheim  considered  them 
monoplanetic,  but  Hartog  (’87)  was  right  in  stating  them  to  be  diplan¬ 
etic  (as  Saprolegnia  corcagiensis).  Sexual  reproduction  has  never  been 
observed. 

As  a  subject  for  the  demonstration  of  protoplasmic  rotation  this 
plant  has  no  superior.  Unlike  the  Saprolegniaceae  the  strongly  granular 
protoplasm  is  in  constant  motion  and  is  easily  observed  even  by  inexperi¬ 
enced  students.  We  have  found  the  plant  in  Chapel  Hill  not  only  in 
sewers,  etc.,  where  it  may  be  had  at  any  time,  but  also  rarely  in  such 
clean  streams  as  Battle’s  brook  and  the  brook  behind  the  athletic  field. 

Kolkwitz  (’03)  has  studied  the  culture  requirements  and  physiology  of 
this  species,  and  has  also  published  a  condensed  statement  of  his  results 
(’03a,  p.  147).  For  illustrations  see  Humphrey  (’92),  pi.  20,  figs.  115-118; 
Pringsheim  (’60),  pi.  23,  figs.  6-10,  and  pi.  25;  and  Biisgen  (’82),  figs. 
9-15.  For  other  cytological  data  see  Dangeard  (’90),  p.  118,  pi.  6,  figs. 
24-3E 


APODACHLYA  Pringsheim,  1883,  p.  289. 

Hyphae  constricted  into  segments  of  variable  length,  more  slender 
than  in  Leptomitus,  the  branching  taking  place  from  any  point  in  a  seg¬ 
ment,  but  usually  near  the  distal  end.  Sporangia  swollen,  pyriform, 
oval  or  spherical.  In  three  species  spherical  resting  bodies  are  known 
with  the  contents  entirely  filling  them,  and  we  regard  these  as  true 
oogonia  containing  a  single  egg;  in  A.  completa  (probably  not  an  Apod- 
achlya)  larger  oogonia  are  formed  with  several  eggs. 

Four  species  have  been  described,  but  in  only  one,  A.  pyrifera  Zopf 
(’88,  p.  362)*,  has  the  structure  heretofore  been  well  known.  See  also 
Petersen  (To,  p.  526).  The  others  are  A.  brachynema  (see  below),  A. 
punctata  Minden  (’12,  p.  586,  figs,  b-d  on  p.  580),  a  very  doubtful  species, 
and  A.  completa  Humphrey  (’93),  which  was  referred  to  this  genus  with 
some  doubt  as  the  sporangia  were  not  found.  We  include  a  description 
of  only  the  species  we  have  found.  For  the  others  see  the  literature 
cited  above  and,  in  addition,  Fischer  (’92,  p.  373). 

Key  to  the  Species 

Oogonia  present,  each  containing  several  eggs . A.  completa 

Resting  bodies  (oogonia?)  entirely  filled  by  the  contents  which  is  organized  like  a  single  egg. 

*  The  name  A  podachlya  pyrifera  is  first  used  on  p.  367,  and  the  plate  is  labelled  Lep¬ 
tomitus  pyrifera. 


APODACHLYA 


i/3 


Resting  bodies  in  greater  part  borne  on  the  tips  of  the  main  hyphae;  spores  usually  en¬ 
cysting  at  the  mouth  of  the  pyriform  to  spherical  sporangia . A.  pyrifera 

As  in  A.  pyrifera,  but  the  oogonial  membrane  distinctly  punctate  (?) . A.  punctata 

Resting  bodies  in  greater  part  borne  on  short,  moniliform,  lateral  branches;  spores  usually 
swarming  at  once  on  leaving  the  pyriform  to  spherical  sporangia. .A.  brachynema 


Apodachlya  brachynema  (Hildb.)  Pringsheim.  Ber.  d.  Deutsch.  Bot. 
Gesell  1:  289.  1883. 

Leptomitus  brachynema  Hildebrand.  Jahrb.  f.  wiss.  Bot.  6:  261,  pi. 
16,  figs.  12-13.  1867. 

Apodya  brachynema  (Hildb.)  Cornu.  Ann.  Sci.  Nat.,  Series  5,  15:  14. 
1872. 


Plate  59 

Main  hyphae  slender,  the  segments  about4.5-8.5p.thickand  110-185;;. 
long  on  termite  ants,  but  4-23.4  x  20-150^  on  corn  meal  agar,  becoming 
shorter  near  the  sporangia  as  a  rule,  the  protoplasm  moderately  dense 
and  with  small  refractive  drops  nere  and  there;  branching  rather  sparsely 
from  any  point  on  the  segments,  but  usually  near  the  distal  end.  Spor¬ 
angia  terminal,  single  or  rarely  two  or  three  in  a  row,  swollen,  pyriform 
or  oval  or  spherical  on  termite  ants,  about  23-29^  thick  and  23-46;;  long, 
renewed  by  sympodial  branching,  opening  by  a  distinct  papilla  formed  a 
few  minutes  before  discharge  of  spores;  papilla  usually  apical  in  the 
longer  sporangia,  either  apical  or  lateral  in  the  short  or  spherical  ones. 
Spores  few,  about  8-20,  short-oval,  in  our  cultures  nearly  always  swimming 
sluggishly  and  aimlessly  for  a  few  minutes  with  two  apical  cilia  on  emerg¬ 
ing,  then  encysting  and  swimming  again  after  a  rest;  diameter  8.5-10;;. 
when  encysted.  Resting  bodies  (oogonia)  formed  plentifully  on  the  tips 
of  short,  lateral,  jointed  branches  from  the  main  hyphae,  spherical  or 
very  rarely  short  pyriform,  23.5-29;;.  thick,  smooth,  dense,  at  first  nearly 
homogeneous,  then  forming  a  number  of  fat  droplets  and  finally  one 
eccentric,  conspicuous  droplet  as  in  the  eccentric-egged  Achlyas;  wall 
unpitted,  about  i.8;jl  thick;  the  suboogonial  cell  (antheridium)  as  a  rule 
nearly  spherical,  at  first  denser  than  the  other  members  of  the  chain, 
then  discharging  its  contents  into  the  oogonium  and  becoming  quite 
empty  before  the  maturation  of  the  egg. 

Found  in  Chapel  Hill  but  once,  in  a  marsh  at  the  foot  of  Lone  Pine 
hill,  collection  No.  2,  February  17,  1921.  It  appeared  late  along  with  Dic- 
tyuchus  and  an  invading  sterile  fungus  with  bacteria  on  a  termite.  After 
considerable  difficulty  it  was  got  in  pure  culture  and  is  being  carried  on. 
Thaxter  (’96,  p.  325)  reports  this  species  and  A.  pyrifera  from  New 
England. 

Of  Apodachlya  brachynema  Hildebrand  says  that  in  addition  to 
the  sporangia  he  noted  at  a  somewhat  later  stage  spherical  cells  on  the 
ends  of  .short  side  branches,  these  cells  filled  with  granular  stuff,  and 
he  suggests  that  they  may  be  oogonia,  though  their  further  development 
was  not  noted.  He  also  shows  (fig.  23)  one  such  body  on  the  end  of  a 


174 


THE  SAPROLEGNIACEAE 


2-celled  stalk  very  like  the  oogonia  of  our  plant.  The  sporangia  are 
also  like  the  majority  in  ours  and  not  all  spherical;  some  are  oval.  He 
did  not  see  the  spores  escape  or  swim,  but  he  shows  no  spores  at  tips  of 
sporangia  and  several  sporangia  are  drawn  with  one  or  more  retained  inside. 
He  says  that  about  six  are  formed.  He  shows  several  sporangia  (as  many 
as  four)  in  a  close  group  by  budding  below  as  in  ours,  and  as  many  as 
three  in  a  row  in  one  case.  His  figures  are  so  nearly  like  ours  that  we 
must  let  our  plant  go  as  4.  brachynema.  Pringsheim,  it  is  true  (1.  c.,  p. 
289),  says  that  in  this  species  he  has  observed  that  the  spores  are  formed 
not  as  in  Saprolegnia  but  as  in  Achlya.  Tiesenhausen ’s  description  and 
figure  of  the  variety  major  represent  our  plant  well,  but  as  his  variety 
is  based  on  size  of  threads  and  sporangia  and  as  our  plant  connects 
these  sizes  up  with  those  of  the  type  it  is  probable  that  this  variety  is 
only  a  form. 

Zopf’s  good  description  and  figures  of  A.  pyrifera  clearly  exclude 
our  plant  on  two  main  points.  In  the  former  the  majority  of  the  oogonia 
are  borne  on  the  tips  of  main  threads,  others  not  so  borne  are  either 
sessile  on  the  side  of  main  hyphae  or  with  a  single  short  stalk  cell.  The 
spores  are  described  as  encysting,  as  a  rule,  in  a  group  at  the  sporan¬ 
gium  mouth,  or  less  often  swarming  at  once  on  emerging.  In  the  latter 
the  oogonia  are  nearly  all  borne  on  rather  short  lateral,  more  or  less 
moniliform  branches  composed  of  a  few  short  segments.  A  culture 
shows  a  peripheral  series  of  sporangia  with  the  oogonia  forming  in  much 
larger  numbers  on  laterals  from  the  same  hyphae  nearer  the  substratum. 
Spherical  sporangia  may  be  distinguished  from  young  oogonia  before 
the  spore  initials  appear  by  the  longer  and  clearer  cell  below  them. 

Minden’s  species,  A.  punctata ,  is  more  than  doubtful.  He  separates 
it  only  on  the  punctate  membrane  of  the  resting  spore  (oogonium) ;  but,  so 
far  as  his  figures  show,  this  punctation  is  nothing  more  than  the  emul¬ 
sified  contents  of  the  young  oogonium,  a  condition  shown  also  by  Zopf 
for  A.  py  riper  a. 

The  spherical  resting  bodies  called  by  Zopf  “  Dauersporen”  or  gem¬ 
mae  are,  we  believe,  oogonia  both  in  his  plant  and  in  ours.  Tiesenhausen 
comes  to  the  same  conclusion  forZL  pyrifera  (1.  c.,  p.  298).  We  know  of 
no  gemmae  in  this  or  related  groups  which  have  thick  walls  and  undergo 
a  maturation  within  like  an  egg.  Moreover,  as  shown  below,  there  is 
good  reason  to  believe  that  fertilization  occurs. 

Observations  of  threads  on  a  corn  meal  agar  plate  show  that  the 
suboogonial  cells  reach  their  final  size  before  the  young  oogonium  ap¬ 
pears.  The  oogonium  appears  as  a  very  small  globular  tip  on  the  end 
of  the  distal  stalk  cell.  The  protoplasm  can  be  seen  passing  from  the 
hyphal  segment  through  the  rounded  stalk  cells  into  the  growing  oogo- 


PLATE  59 


PLATE  59 

Apodachlya  brachynema 

Figs,  i,  2.  Mature  oogonia  on  their  moniliform  branches.  One  has  two  oil  drops.  X503. 
Fig.  3.  Two  mature  oogonia  and  one  immature.  X  503. 

Fig.  4.  A  nearly  mature  oogonium.  X  810. 

Fig.  5.  An  oogonium  with  a  large  vacuole  in  an  early  stage  of  maturation.  X  810. 

Fig.  6.  An  empty  sporangium  with  a  young  one  by  it.  X  503. 

Fig.  7.  A  sporangium  approaching  maturity.  X  810. 

Fig.  8.  A  long,  empty  sporangium  with  a  young  spherical  one  on  the  same  thread.  X  278. 
Figs.  9,  10.  Sporangia  with  the  hypha  continued  beyond.  X  503. 

Fig.  11.  A  sporangium  after  opening  with  one  spore  retained.  X  503. 

Fig.  12.  A  sporangium  after  opening  with  4  spores  retained  and  a  young  sporangium  by  it. 

x  503- 

Fig.  13.  A  sporangium  that  failed  to  open,  the  mature  spores  still  retained.  X  503. 

Fig.  14.  An  empty  sporangium.  X  503. 

Fig.  15.  Two  sporangia  in  a  row.  X  278. 

Fig.  16.  A  joint  of  an  old  thread  with  the  opening  stopped  by  a  plate  of  cellulin.  X  810. 
Fig.  17.  A  branched  hypha  in  active  growth.  X  503. 

Fig.  18.  A  spore  in  first  swimming  stage  with  two  apical  cilia.  X  8 10. 

Fig.  19.  A  spore  emerging  from  its  cyst.  X  810. 

Fig.  20.  A  spore  in  the  second  swimming  stage  (cilia  not  shown).  X  810. 

Fig.  21.  A  spore  sprouting  after  the  second  encystment.  X  810. 

Fig.  22.  A  sporangium  with  some  of  the  spores  retained,  some  held  at  the  mouth  (a  few  had 

swum  away).  X  503. 


PLATE  59 


APODACHLYA  BRACHYNEMA. 


APODACHLYA 


175 


nium.  An  oogonium  grows  from  its  first  visible  size  to  its  mature  size 
in  about  eight  hours.  At  the  time  when  the  oogonium  reaches  its  mature 
size  the  contents  of  all  the  stalk  cells,  except  the  one  next  the  oogonium, 
become  less  dense,  while  the  oogonium  and  its  adjoining  cell  are  very 
dense  and  homogeneously  mottled.  After  a  short  rest  the  contents  of 
the  dense  cell  pass  over  into  the  oogonium.  This  apparent  fertilization 
requires  from  three  and  one-half  to  five  hours.  Then  after  another 
short  rest  organization  of  the  contents  begins.  When  the  oogonium 
finally  falls  away  this  subspherical  cell  adjoining  goes  with  it,  the  chain 
breaking  below  it.  There  is  also  a  very  significant  change  going  on  in 
the  oogonium  during  the  reduction  of  the  protoplasm  in  the  adjacent 
cell.  A  light  spot  appears  in  the  proximal  end  in  the  hitherto  homogene¬ 
ous  egg  and  this  persists  until  nearly  all  the  protoplasm  has  disappeared 
from  the  cell  below.  It  then  disappears  as  the  maturation  changes  set  in. 
While  Zopf  refers  to  the  possibility  of  the  cells  he  found  attached  to 
the  gemmae  being  antheridia,  he  concludes  that  they  are  more  prob¬ 
ably  resting  zoospores  or  invading  organisms  of  other  kinds.  They 
may  well  be  antheridia. 

Our  plant  does  fairly  well  in  culture  on  termites  in  boiled  well 
water,  and  will  grow  well  but  slowly  on  corn  meal  agar.  The  sporangia 
are  very  whimsical  about  opening  at  room  temperature  (about  60-70°  F.), 
but  rarely  fail  to  discharge  their  spores  if  kept  in  an  ice  box. 

On  corn  meal  agar  many  of  the  segments  become  dumb-bell  shaped. 
One  segment  measured  23. 4;j.  thick  at  proximal  end,  I4;ji  in  middle,  21  \x 
at  distal  end,  and  was  105^  long.  The  internodes  of  young  threads  are 
open,  as  is  evidenced  by  the  fact  that  protoplasmic  streams  can  be  seen 
passing  from  one  segment  to  another,  while  those  of  old  threads  are 
closed  by  a  cellulin  plug.  Usually  there  are  two  or  three  globules  of 
cellulin  in  each  segment.  The  globules  are  moved  about  by  the  action 
of  protoplasm,  either  pushed  along  in  large  segments  or  rotated  in  small 
ones.  Old  segments  are  usually  very  dense  with  protoplasm,  which 
moves  almost  imperceptibly.  Occasionally  a  sparsely  filled  segment 
will  be  found  between  two  densely  filled  ones;  in  it  the  protoplasm  will 
be  in  active  motion, limited  to  its  own  walls  by  the  cellulin  plugs  at  the 
internodes.  It  is  on  densely  filled  segments  that  oogonial  branches 
are  borne. 

The  spores  on  emerging  are  forced  out  under  pressure,  as  usual  in 
the  water  molds,  but  the  pressure  becomes  so  weak  before  all  are  out 
that  several  may  swim  around  in  the  sporangium  a  few  minutes  before 
getting  out,  and  the  last  one  or  two,  rarely  more,  are  often  retained 
inside  and  encyst  there  after  a  few  minutes’  swim.  Inside  the  sporan¬ 
gium  the  spores  are  subspherical  before  emerging,  but  in  passing  out 


176 


THE  SAPROLEGN 1 ACEAE 


of  the  smaller  opening  they  become  oblong,  only  to  become  short-pip¬ 
shaped  again  as  they  swim  away  with  two  apical  cilia.  This  first  swim¬ 
ming  is  very  deliberate  and  apparently  quite  aimless  and  continues 
for  only  a  few  minutes.  After  encysting  the  spores  emerge  after  a  time 
and  swim  again  with  a  clear  spot  on  one  side  as  usual.  In  this  stage 
the  swimming  is  much  more  regular,  the  spores  going  straight  forward 
at  a  very  steady  gait.  On  encysting  again  the  spores  may  sprout. 

On  a  bit  of  corn  meal  in  sterilized  well  water  young  threads  produced  oval  sporangia 
about  the  same  size  as  those  on  termites  and  pear-shaped  oues  about  35  X  6op.. 
These  sporangia  on  agar  produced  long  papillae,  6—7  X  50— 400;x,  but  the  spores 
while  formed  rarely  escaped. 

A  culture  on  a  piece  of  boiled  corn  grain  in  sterilized  well  water  produced  oogonia  in  gieat 
abundance. 


SAPROMYCES  Fritsch,  1893,  P-  420. 

Plant  arising  as  a  single,  slender  basal  cell  attached  by  rhizoids  and 
branching  at  the  tip  into  two  or  more  similar  segments  which  are  con¬ 
stricted  at  the  point  of  origin  and  which  rebranch  again  one  or  more 
times  in  the  same  way.  Sporangia  single  or  in  groups,  apical  or  lateral  from 
the  continuation  of  the  threads,  elongated  clavate  to  nearly  cylindrical, 
the  monoplanetic  spores  escaping  by  an  apical  papilla.  Oogonia  in  some 
forms  (or  at  some  seasons?)  absent,  when  present  single  or  in  whorls  at 
the  nodes,  pyriform,  often  encrusted.  Egg  single.  Antheridia  borne  on 
long  or  short  branches  which  are  often  twisted,  androgynous  or  diclinous, 
applied  to  the  tip  of  the  oogonia  and  sending  a  tube  to  the  egg.  Three 
species  are  known  as  mentioned  above  under  the  family,  also  a  sterile 
plant  which  is  thought  by  Thaxter  to  be  a  form  of  S.  Reinschii.  This 
sterile  form  was  found  by  Mr.  Couch  near  Wilmington  and  the  descriptive 
notes  were  made  from  his  observations. 

Sapromyces  Reinschii  (Schroet.)  Fritsch.  Osterr.  bot.  Zeitschr.  43:420. 

1893. 


Plate  60 

Hyphae  divided  into  segments  of  unequal  length  by  incomplete 
constrictions,  the  connection  between  the  segments  being  closed  by  a 
cellulin  plug;  branched  repeatedly,  the  new  branches  often  arising  in 
whorls,  not  rarely  dichotomously  branched;  5-1  5;j.  thick,  most  about 
1  Oja.  Sporangia  apical  or  rarely  lateral,  single  or  in  clusters  of  as  many 
as  six,  very  variable  in  shape  and  size,  sub-cylindrical  to  oval,  usually 
elongate-elliptical;  14-28  x  30-140^,  most  about  25  x  I25;j..  Spores  usually 
completely  formed  in  the  sporangium  before  emerging,  and  then  emerging 
separately  with  the  ciliated  end  directed  backward  (not  rarely  the  entire 
contents  of  the  sporangium  discharged  as  a  naked  mass  before  the  spore 


PLATE  60 


PLATE  60 

Sapromyces  Reinschii 

Figs.  I,  2,  3,  4.  Sporangium  showing  stages  of  >pore  formation. 

Fig.  5.  Sporangium  with  precipitate  on  wall. 

Fig.  6.  Habit  of  hyphae  and  sporangia. 

Fig.  7.  Sporangium  ontaining  encysted  spores. 

Fig.  8.  Spore  which  emerged  as  in  fig.  12  or  14. 

Fig.  9.  Sporangium  showing  emerging  spores. 

Fig.  10.  Sporangium  arising  in  a  whorl  of  hyphal  segments. 

Fig.  11.  Small  sporangia;  one  discharging  two  spores. 

Fig.  12.  Sporangium  discharging  partly  formed  ‘pores  through  a  papilla,  leaving  pre¬ 
cipitate. 

Fig.  13.  Sporangia;  one  containing  sprouting  spores. 

Fig.  14.  Sporangium  discharging  contents  as  an  undifferentiated  mass. 

Figure  6  X  107;  others  X  447. 


PLATE  60 


SAPROMYCES  REINSCHII. 


SAPROMYCES 


1 77 


origins  appear,  and  then  spores,  irregular  in  shape  and  size,  formed  out 
in  the  water) ;  escaping  through  a  terminal  pore  or  not  rarely  through  a 
papilla;  biciliate,  monoplanetic,  shaped  as  in  Sciprolegnia  or  Achlya, 
8-14H  thick,  normally  about  10a.  No  oogonia  or  antheddia  observed 
in  our  form. 

Found  only  once  by  us  and  then  growing  with  A  chlya  and  Saprolegnia 
in  a  culture  collected  near  Wilmington,  N.  C.  (No.  3  of  December  30, 
1921,  J.  N.  Couch).  Reported  hitherto  in  America  only  at  York,  Maine, 
by  Thaxter  (Bot.  Gaz.  19:  49,  pi.  5.  1894)  on  cones  and  twigs  of  Pinus  in 
a  spring.  Otherwise  recorded  from  Germany  by  Reinsch  on  Viscum 
stems  and  on  algae  (Jahr.  f.  wiss.  Bot.  11:  298,  pi.  15,  figs.  1-11,  1878, 
as  Naegelia  species  I  and  species  II),  again  from  Luneburg,  Germany, 
by  Minden  on  coniferous  twigs  (’12,  p.  589,  figs,  na  and  11b  on  p.  590), 
and  from  Denmark  by  Petersen  (Ann.  Myc.  8:  527.  1910).  Minden 
says  that  the  plant  was  also  found  by  Claussen.  Thaxter  found  a  strain 
of  this  plant  which  bore  sporangia  luxuriantly  but  showed  no  indication 
of  any  form  of  sexual  reproduction.  Later  in  the  season  he  secured 
additional  specimens  from  the  same  spring,  one  of  which  furnished  fine 
examples  of  the  curious  oogonia  and  antheridia.  Petersen  also  found 
both  sexual  and  sterile  individuals,  and  he  states  that  the  sporangia 
were  more  cylindrical  in  the  sterile  ones,  suggesting  that  two  species 
may  be  involved.  Thaxter  considers  both  forms  to  be  conditions  of  a 
single  species  in  which  the  sporangia  are  quite  variable.  There  seems  to 
be  little  doubt  that  our  plant  is  identical  with  the  sexually  sterile  strain 
of  Thaxter  and  also  that  of  Petersen. 

Thaxter  describes  the  primary  axis  as  originating  “as  a  single  basal 
cell  or  segment  which  is  attached  by  its  roughened  surface  directly  to 
the  substratum,  without  rhizoidal  outgrowths.  It  is  often  more  or  less 
bent  and  distorted  but  otherwise  undifferentiated  ...”  This  basal  cell  was 
not  observed  in  our  original  culture,  but  when  the  fungus  was  cultivated 
in  corn  juice  or  pea  juice  the  basal  segment  became  obvious  and  was 
seen  to  be  slightly  swollen  and  distorted. 

There  are  certain  peculiarities  in  the  discharge  of  the  sporangia  that 
are  worthy  of  comment.  The  contents  of  the  sporangium  may  be  com¬ 
pletely  formed  into  spores  within  the  sporangium  and  the  spores  emerge 
to  swim  away  immediately  upon  gaining  their  exit  (fig.  9),  or  the  con¬ 
tents  of  the  sporangium  may  be  discharged  with  the  spores  partly  formed, 
to  complete  their  formation  out  in  the  water  at  the  sporangial  mouth 
(fig.  12),  or  the  sporangial  contents  may  be  discharged  as  an  undifferen¬ 
tiated  naked  mass  of  protoplasm,  the  spores  forming  outside  (fig.  14). 
All  three  methods  of  sporangial  discharge  may  be  taking  place  syn¬ 
chronously  in  the  same  culture.  If  the  spores  emerge  when  they  are  only 
partially  differentiated  a  heavy  precipitate  is  left  on  the  walls  of  the  spor- 


1 78 


THE  SAPROLEGNIACEAE 


angium(figs.  5  and  12) ;  this  precipitate  is  not  left  if  the  spores  are  completely 
formed  before  discharge  or  if  the  contents  discharge  as  an  undifferentiated 
mass  (figs.  9  and  14).  Thaxter  notes  only  the  internal  formation  of  the 
spores  and  their  escape  one  by  one  from  the  sporangium,  swarming  at 
once.  On  the  other  hand,  Petersen  states  that  the  spores  “emerge  in 
a  great  vesicle  which  soon  bursts.”  This  is  contrary  both  to  Thaxter’s 
observations  and  to  ours.  We  find  that  in  case  the  spore  mass  escapes 
before  the  differentiation  of  the  spores  the  mass  is  not  surrounded  by  a 
vesicle  but  lies  naked  in  the  water.  Minden  takes  a  somewhat  inter¬ 
mediate  position,  stating  that  the  spores  escape  in  a  bladder  which, 
however,  soon  bursts  so  that  most  of  the  spores  issue  directly  from  the 
sporangium.  He  finds  the  spores  to  have  the  form  shown  in  the  second 
swimming  stage  of  the  Saprolegniaceae,  with  the  cilia  arising  from  a 
depression  on  one  side.  The  scantiness  of  our  material  prevented  our 
observing  their  form  with  certainty. 

This  rare  and  peculiar  plant  grows  very  poorly  under  laboratory 
conditions.  Attempts  were  made  to  cultivate  it  on  all  the  subtrata  on 
which  Achlyas  and  Saprolegnias  ordinarily  grow  well,  as,  for  example, 
corn  meal  agar,  termite  ants,  bits  of  boiled  corn  grain,  peas  and  beans,  but 
without  successful  results.  Unsuccessful  attempts  were  also  made  to  grow 
the  fungus  on  pieces  of  pine  cones  and  twigs  both  green  and  dry.  The 
plant  grows  slowly  in  vegetable  juices  obtained  by  boiling  corn  grains 
or  peas,  and  it  was  from  such  cultures  and  from  the  original  collection 
that  our  observations  were  made. 

For  svnonomy  and  other  references  see  Thaxter,  as  above  cited. 


MONOBLEPHARIDACEAE* 

Phycomycetes  living  in  water  and  saprophytic  on  plant  or  animal 
remains.  Mycelium  slender,  branched,  not  divided  into  cells  or  con¬ 
stricted  at  intervals.  Sporangia  apical;  zoospores  with  one  or  two  cilia. 
Oogonia  containing  only  one  egg  each  and  opening  at  maturity  to  admit 

*  We  call  attention  here  to  the  remarkable  genus  Myriablepharis  Thaxter  (Bot.  Gaz.  20: 
482,  pi.  31,  figs.  1-5.  1895).  It  is  of  quite  uncertain  position  and  Thaxter  does  not  assign  it 
to  any  family.  According  to  him  the  zoospores  are  ciliated  all  over  as  in  Vaucheria,  a  con¬ 
dition  not  known  in  any  other  fungus.  No  sexual  reproduction  has  been  observed.  The 
plant  has  been  found  more  recently  in  Breslau,  Germany,  by  Minden  (’12,  p.  476)  who 
confirms  Thaxter’s  observations.  He  is  inclined  to  think,  however,  that  the  remarkable 
spores  are  not  those  of  the  plant  but  of  a  parasitic  protozoan,  the  fungus  being  a  species  of 
Pythium.  Lotsy  (’07,  p.  125)  has,  apparently  without  sufficient  reason,  placed  the  genus  in 
the  Monoblepharidineae.  In  this  place  we  might  also  refer  to  the  genus  Rheosporangium  Edson 
(Journ.  Agric.  Research  4:  279.  1915)  which  he  places  in  the  Saprolegniaceae.  We  can  see  no 
reason  why  it  should  not  be  considered  a  species  of  Pythium. 


MONOBLEPHARIS 


179 


the  sperms.  Antheridia  formed  near  the  oogonia,  producing  uniciliate 
sperms  which  escape  and  fertilize  the  eggs.  The  fertilized  egg  matures 
within  the  oogonium  or  passes  out  of  it  and  matures  attached  to  its  tip. 

For  many  years  this  family  contained  only  the  remarkable  genus 
Monoblepharis  established  by  Cornu  in  1871,  (p.  59)  and  later  described 
more  fully  and  figured  (’72).  Lagerheim  in  1900  (pp.  32  and  39)  pro¬ 
posed  the  genus  Diblepharis  to  contain  the  two  American  species  de¬ 
scribed  by  Thaxter  (’95).  For  other  important  literature  see  Fischer 
(’92,  p.  378);  and  Woronin  (’04).  Tiesenhausen  (’12)  finds  M.  poly¬ 
morpha  and  M.  macrandra  and  gives  a  figure  of  the  former.  The  genus 
Gonapodya  of  Fischer,  placed  by  him  in  the  Monoblepliaridaceae ,  has 
been  shown  by  Thaxter  (’95a)  to  be  better  disposed  of  in  the  Leptomitaceae 
(which  see).  We  have  not  found  any  species  of  this  family,  but  give 
below  an  enumeration  of  the  genera  and  species  for  the  convenience  of 
students  :f 


MONOBLEPHARIS  Cornu,  1871,  p.  59. 

Zoospores  with  one  cilium;  all  the  contents  of  the  sporangia  and 
oogonia  entering  into  their  products. 

Sub-genus  Eumonoblepharis  Lagerheim.  Fertilized  eggs  maturing  within 
the  oogonia.  Includes  only  one  species. 

M.  sphaerica  Cornu.  Europe. 

Sub-genus  Exoosporci  Lagerheim.  Fertilized  eggs  moving  out  of  the 
oogonium  and  maturing  outside. 

M.  polymorpha  Cornu.  Europe  and  New  England  (Thaxter). 

M.  polymorpha  var.  macrandra  Lagerheim  (1.  c.,  p.  35)  [M.  macran¬ 
dra  (Lagerh.)  Woronin.]  Europe. 

M.  brachyandra  Lagerheim  (1.  c.,  p.  37).  Europe. 

In  the  two  following  imperfectly  known  species  the  sexual  repro¬ 
duction  has  not  been  seen  and  their  relationships  are  therefore  uncer¬ 
tain  : 

M.  regignens  Lagerheim  (p.  39). 

M.  ovigera  Lagerheim  (p.  39). 

Woronin  (’04)  figures  an  intermediate  form  that  he  thinks  may  be 
a  hybrid  between  M.  p.  var.  macrandra  and  M.  sphaerica. 

DIBLEPHARIS  Lagerheim,  1900,  p.  39. 

Zoospores  with  two  cilia,  on  escaping  leaving  a  drop  of  oil  in  the 
sporangium.  Oogonium  on  opening  discharging  a  part  of  its  proto- 

f  The  plant  described  by  Hine  as  Monoblepharis  lateralis  (Am.  Quart.  Micr.  Journ. 
1:  141.  1879)  is  evidently  not  of  this  genus  but  probably  a  Saprolegnia  which  was  incor¬ 
rectly  observed  and  interpreted. 


i8o 


THE  SAPROLEGXIACEAE 


plasm  into  the  water,  the  remainder  (larger  part)  forming  the  egg  which 
matures  within  the  oogonium. 

D.  insignis  (Thaxter)  Lagerheim  (p.  40).  Massachusetts  and  Maine. 

D.  fasciculata  (Thaxter)  Lagerheim  (p.  40).  Massachusetts. 

BLASTOCLADIACEAE 

This  family  has  been  based  on  a  single  genus,  Blastocladia,  whose  sys¬ 
tematic  position  has  been  and  still  is  somewhat  doubtful.  Thaxter  (’96) 
thinks  that  the  genus  should  be  placed  either  under  the  Pythiaceae  or  in 
a  new  family  of  its  own.  Minden  (’12,  p.  506)  and  Petersen  (To,  p. 
532)  recognize  the  family  Blastocladiaceae  and  it  would  seem  as  well  to 
follow  them  for  the  present.  We  are  also  including  in  the  family  the  genus 
Allomyces  Butler,  placed  by  the  author  in  Leptomitaceae.  Except  for  a 
few  additions  made  to  include  Allomyces  the  following  diagnosis  is  taken 
with  a  few  changes  from  Minden: 

Saprophytic  fungi  living  in  water  on  substrata  of  plants.  Mycelium 
unicellular,  or  in  Allomyces  with  complete  septa  at  the  nodes,  rather 
abundantly  branched,  separated  usually  into  a  main  axis  and  secondary 
axes  and  sometimes  having  sterile,  thin  threads  of  unknown  function. 
Sporangia  usually  ellipsoid  to  cylindrical  in  shape,  often  clearly  forming 
sympodia  through  the  shortening  of  the  threads  upon  which  they  grow, 
but  also  thickly  crowded  together,  seldom  growing  through  each  other. 
Zoospores  ellipsoid  to  egg-shaped  with  broad  blunt  ends  and  one  (or 
two?)*  cilia  on  the  broader,  colorless  end,  the  other  end  containing 
small  granules;  emerging  with  force  through  an  apical  opening  in  the 
sporangium  and  swimming  away,  then,  after  being  surrounded  by  a  mem¬ 
brane,  sprouting;  while  entering  into  the  resting  condition  there  is  amoe¬ 
boid  motion.  Sexual  reproduction  does  not  take  place.  Instead  there 
are  formed  resting  bodies  in  the  shape  usually  of  broad  ellipsoid 
cells  that  coincide  in  origin  and  position  with  sporangia,  but  have  a 
membrane  consisting  of  two  sheaths  of  which  the  outer  one  is  smooth 
and  colorless  while  the  inner  one  appears  finely  and  regularly  dotted  (or 
punctured).  At  maturity  these  cells  either  fall  away  as  a  whole  or  the 
thin,  colorless,  outer  sheath  splits  at  the  tip  and  allows  the  escape  of  the 
inner  sheath  and  its  contents.  After  a  time  the  resting  cells  germinate 
by  the  cracking  of  the  thick  brown  wall,  so  as  to  allow  the  protrusion  of 
a  delicate  bladder  in  which  the  spores  develop.  Spore  discharge,  how¬ 
ever,  has  not  yet  been  observed. 


BLASTOCLADIA  Reinsch,  1878,  p.  291. 

Characters  of  the  family  except  that  the  plant  body  is  never  septate. 
Four  species  have  been  described,  all  of  which  are  treated  in  Minden’s 

*  Thaxter  finds  zoospores  to  have  two  cilia  as  a  rule  in  B.  Pringsheimii. 


ALLOMYCES 


1 8 1 


work.  Thaxter  finds  B.  Pringsheimii  both  at  Cambridge,  Mass.,  and  at 
Kittery  Point,  Me.  He  also  describes  a  new  species,  B.  ramosa  from 
Kittery  Point.  The  four  described  species*  we  list  below,  with  references 
to  authors  and  important  figures,  omitting  full  descriptions,  which  may 
be  easily  found  under  the  references: 

Blastocladia  Pringsheimii  Reinsch  ’78,  p.  291,  pi.  16,  figs.  1-13.  See  also  Thaxter  ’96,  p. 
51,  pi.  3,  figs.  I— 1 3 ;  and  Petersen  To,  p.  532,  fig.  10.  Sporangia  much  elongated,  rest¬ 
ing  bodies  with  thick  and  pitted  wall,  not  slipping  from  a  sheath  at  maturity;  sterile, 
slender  filaments  often  present  among  the  reproductive  bodies. 

Blastocladia  ramosa  Thaxter  ’96,  p.  50,  pi.  3,  figs.  14-16.  Sporangia  shorter;  resting  bodies 
with  thin  and  scarcely  pitted  wall;  sterile  filaments  absent. 

Blastocladia  rostrata  Minden  ’12,  p.  604.  Much  like  B.  Pringsheimii ,  but  resting  bodies 
slipping  from  sheath  at  maturity. 

Blastocladia  prolifera  Minden  T2,  p.  604.  Much  like  B.  ramosa,  but  sporangia  proliferat¬ 
ing  internally,  as  in  Saprolegnia:  the  only  species  with  this  habit.  Resting  bodies 
slipping  from  a  sheath  at  maturity. 


ALLOMYCES  Butler,  1911,  p.  1023.4 

Plant  small,  slender,  the  short  or  long  stalk  not  conspicuously  dif¬ 
ferentiated;  branches  usually  dichotomous,  often  verticellate  in  groups 
of  3-5,  separated  from  the  nodes  by  distinct  and  complete  septa,  not 
constricted  at  intervals;  in  vigorous  cultures  repeating  the  branching 
in  the  same  way  to  form  a  complex  plant.  Sporangia  oval,  terminal, 
sympodially  arranged,  not  rarely  in  chains  of  several,  often  clustered 
by  the  shortening  of  the  branches,  which  continue  the  stem  by  one  or 
more  lateral  buds  beneath.  Spores  biciliate  at  times,  but  the  two  cilia 
so  closely  approximated  or  fused  as  usually  to  appear  as  one.  Resting 
bodies  borne  in  the  same  way  as  the  sporangia  and  of  the  same  size  and 
shape,  at  maturity  enclosed  in  a  thin,  hyaline  sheath  out  of  which  they 
finally  fall  through  an  apical  slit;  the  wall  brown  and  conspicuously 
pitted  as  in  Blastocladia :  the  whole  representing  a  thin-walled  oogonium 
completely  filled  with  a  thick-walled  parthenogenetic  egg,  or  a  resting 
sporangium  as  thought  by  Barrett  (’12a,  p.  365). 

A  saprophytic  aquatic  of  anomalous  structure  and  differing  from  all 
other  Phycomycetes  in  the  regular  and  normal  septation  of  the  plant  body. 

*  A  fifth,  B.  strangulata  Barrett,  is  treated  here  as  a  synonym  of  Allomyces  arhus- 
cula,  which  see  below. 

f  The  following  treatment  of  the  genus  and  species,  as  well  as  the  plate,  is  taken  with 
slight  modification  from  Coker  and  Grant  in  Journ.  E.  Mitchell  Sci.  Soc.  37:  180.  1922 
(as  Septocladia  dichotoma). 


THE  SAPROLEGNIACEAE 


182 

Allomyces  arbuscula  Butler.  Ann.  Bot.  25: 1027,  figs.  1-18.  1911. 

Blastocladia  strangulata  Barrett.  Bot.  Gaz.  54:  353,  pis.  18-20. 

1912. 

Septocladia  dichotoma  Coker  and  Grant.  1.  c. 

Plate  6 I 

Characters  of  the  genus.  Threads  extending  about  3  mm.  from 
the  substratum  on  a  termite  ant,  about  10-37^  thick,  growing  grad¬ 
ually  more  slender  distally  at  each  joint,  basal  joints  35-130(0.  long, 
those  of  central  region  up  to  about  675(0.  long;  tips  blunt,  hyaline.  Spor¬ 
angia  oval,  28-46  x  55—76(0. ;  spores  escaping  singly  or  at  times,  according 
to  Barrett,  in  a  vesicle  that  soon  bursts,  emerging  through  one  or  two 
usually  apical  holes  or  short  papillae,  biciliate  (or  uniciliate  by  fusion 
of  the  two  cilia?),  oval  when  swimming,  with  the  cilia  apical,  monoplanetic, 
amoeboid  before  encysting,  I0[o.  thick  when  at  rest;  sprouting  by  a  slender 
thread.  Resting  bodies  appearing  later  than  the  sporangia  but  of  the 
same  shape,  25-39.2  x  36.3-49.2(0.,  the  conspicuous  pits  apparently 
sunken  from  the  outside  in  regular  fashion  as  in  Blastocladia  Pringsheimii, 
at  maturity  slipping  from  the  thin,  clasping  sheath;  sprouting  into  zoo¬ 
spores  after  a  rest  (Barrett).  The  thick  wall  is  divided  into  two  parts, 
an  outer  layer  (pitted)  about  1.8(0,  thick  and  a  homogeneous  inner  one 
about  i(o,  thick. 

Found  only  once,  October  20,  1921,  on  a  knuckle  bone  of  beef  partly 
covered  with  water,  in  Sparrow’s  pasture,  Chapel  Hill,  N.  C.  (F.  A. 
Grant,  coll.).  Reported  heretofore  only  from  India  (Butler,  1.  c,),  and 
from  Ithaca,  N.  Y.  (Barrett,  1.  c.);  but  Dr.  Weston  of  Harvard  writes 
me  that  he  has  it  from  the  Philippines. 

Butler  places  the  genus  in  the  Leptomitaceae,  but  it  seems  to  us 
that  there  can  be  no  doubt  of  the  close  relationship  of  this  plant  to  Blas¬ 
todadia,  in  which  genus  it  was  placed  by  Barrett.  From  accounts  by 
Butler  and  by  Barrett  there  appears  to  be  practically  no  difference  between 
their  plants  and  ours.  Butler  gives  the  maximum  length  of  the  resting 
spores  as  60[j.,  but  the  difference  is  probably  of  little  or  no  importance. 
We  had  unfortunately  overlooked  these  two  papers  in  recording  our  plant. 
Barrett  gives  interesting  cytological  detail.  He  found  pores  in  the  cross 
walls  of  his  form.  Butler  does  not  record  these  nor  have  we  found  them. 

In  the  form  of  the  sporangia  and  resting  cells  and  in  the  absence  of 
sterile  filaments  among  them  our  plant  resembles  most  closely  B.  ramosa 
and  B.  prolifera .  The  remarkable  resting  bodies  with  their  thick  brown 
strongly  pitted  walls  and  peculiar  habit  of  slipping  at  maturity  from 
the  closely  fitting  sheath  are  so  strikingly  similar  in  structure  and  habit 
to  those  of  B.  rostrata  and  B.  prolifera,  and  in  structure  to  those  of  B. 
Pringsheimii,  that  one  is  convinced  of  their  close  relationship. 

In  a  discharging  sporangium  a  few  spores  that  failed  to  get  out  were 
observed  to  crawl  about  actively  in  an  amoeboid  fashion  for  a  good  while. 


PLATE  61 


PLATE  61 


Allomyces  arbuscula 

Fig.  i.  Empty  sporangia  in  chains.  X  1 54. 

Fig.  2.  Three  sporangia,  one  discharging  spores,  two  empty.  X  420. 

Fig.  3.  Vegetative  branch,  showing  short  joints  and  young  resting  bodies.  X  59. 

Fig.  4.  Optical  section  of  resting  body  and  empty  sporangium  with  two  apertures.  X  420. 
Fig.  5.  Two  spores  showing  cilia.  X  1296. 

Fig.  6.  Spores  showing  amoeboid  movement  before  encysting.  X  810. 

Fig.  7.  Sprouting  spores.  X  1008. 

Fig.  8.  Habit  sketch,  showing  empty  sporangia  and  resting  bodies.  X  96. 

Fig.  9.  Vegetative  tips,  showing  refractive  bodies  and  clear  blunt  tips.  X  150. 

Fig.  10.  Optical  section  of  mature  resting  body  with  empty  sporangium  below.  X  420. 

Fig.  11.  Long,  slender  thread  on  corn  grain,  showing  sympodial  arrangement  of  resting 
bodies.  X  96. 

Fig.  12.  Surface  view  of  resting  body,  showing  pits.  X  420. 

Fig.  13.  Part  of  branch,  showing  thin  sheath  out  of  which  the  resting  body  (Fig.  12) 
has  slipped.  X  420. 

Fig.  14.  Section  of  thick  wall  of  the  resting  body,  showing  the  pits  and  the  sheath  outside. 
X  1296. 

Fig.  15.  Mature  sporangium  just  before  discharge  of  spores.  X  420. 

Fig.  16.  Group  showing  some  sporangia  before  maturity  and  some  after  emptying.  X  96. 


PLATE  61 


ALLOMYCES  ARBUSCULA 


ALLOMYCES 


183 


After  an  hour  they  had  encysted  and  one  had  sprouted.  The  spores  are  of 
a  peculiar  internal  structure,  resembling  closely  those  of  B.  Pringsheimii 
as  shown  by  Thaxter  (1.  c.,  pi.  3,  fig.  11).  Most  of  the  protoplasm  is  at 
the  end  opposite  the  cilia,  the  center  is  almost  clear  and  the  cilia  seem  to 
extend  down  through  the  clear  tip  to  a  protoplasmic  mass  below,  as  shown 
in  our  fig.  5. 

On  an  agar  plate  the  plant  does  not  do  well.  A  few  root-like  threads  grow  out,  branched 
and  with  cross-walls  in  the  older  portions,  and  in  these  older  portions  are  found  resting 
bodies  or  sporangia,  sometimes  fifteen  or  twenty  of  the  latter  in  a  row.  The  repro¬ 
ductive  bodies  are  sometimes  found  in  clusters  or  single  on  short  lateral  stalks. 

On  boiled  corn  agar  the  growth  is  good.  The  threads  are  about  the  same  size  as  on  an  ant 
but  average  longer,  as  much  as  5  mm.,  and  the  protoplasm  is  not  as  dense  as  when 
grown  on  ants.  Threads  at  substratum  as  large  as  I02p,  in  diameter.  Sporangia  are  pro¬ 
duced  better  than  on  ants,  and  resting  bodies  are  so  abundant  that  the  entire  culture 
assumes  a  brick  dust  color  to  the  unaided  eye.  The  resting  bodies  are  at  first  dark  and 
have  numerous  large  oil  droplets.  As  they  get  older  the  walls  assume  a  yellow-brown 
color  and  the  contents  becomes  homogeneous. 


PARASITES  OF  THE  WATERMOLDS 

The  parasites  of  the  wrater  molds  have  been  conveniently  grouped 
by  Fischer  (’92,  p.  149),  and  we  adapt  the  following  from  him  with  the 
addition  of  two  species  of  Olpidiopsis  recently  described.  To  Fischer 
one  may  also  go  for  the  literature.  We  are  describing  more  fully  only 
those  species  wdiich  we  have  had  an  opportunity  to  study  in  the  living 
condition. 

On  hyphae  of  Saprolegnia:  Olpidium  Borzianum;  Pseudolpidium  Saprolegniae;  Olpidi¬ 
opsis  Saprolegniae;  Olpidiopsis  echinata  (See  Petersen  in  Ann. 
Myc.  8:  540.  1910);  Olpidiopsis  major*;  Woronina  polycystis; 
Rozella  septigena. 

On  hyphae  of  Achlya:  Pseudolpidium  jusiforme;  Olpidiopsis  minor;  Olpidiopsis  in¬ 

dex;  Rozella  simulans. 

On  oogonia  of  Saprolegnia 

and  Achlya:  Rhizophidium  carpophilum;  Rhizidiomyces  apophysatus. 

On  Aphanomyces:  Pseudolpidium  aphanomyces. 

On  Rhipidium  spinosum:  Pleolpidium  Rhipidii. 

On  Monoblepharis  poly- 

morpha:  Pleolpidium  Monoblepharidis. 

*  See  Maurizio  (’95),  p.  15,  figs.  4-9.  Grows  on  S.  ferax  and  5.  hypogyna.  This  is 
very  doubtfully  distinct  from  0.  Saprolegniae. 


1 84  THE  SAPROLEGNIACEAE 

Olpidiopsis  Saprolegniae  (Cornu)  amend.  Fischer.  Rabenhorst’s  Ivrypt. 
FI.  1.  part  4:  38,  fig.  4.  1892.  (2nd.  ed.). 

Olpidiopsis  Saprolegniae  Cornu,  in  part.  Ann.  Sci.  Nat.  Series  15, 
5:  145,  pi.  3,  fig.  10.  1872. 

Plate  62,  figs.  7-10 

Sporangia  usually  elliptical  but  sometimes  spherical,  smooth,  very 
variable  in  size,  sometimes  as  much  as  704  through  the  shortest  diam¬ 
eter,  usually  occupying  intercalary  swellings,  but  may  occur  in  oogonia 
or  sporangia;  emptying  by  one  or  more  tubes  which  penetrate  the  host’s 
wall.  Spores  very  minute  and  numerous,  bean-shaped  with  two  lateral 
cilia  (Maurizio  also  finds  two  cilia  in  0.  major),  swimming  rapidly,  emerg¬ 
ing  through  internal  pressure  in  a  slender  stream  and  collecting  at  the 
opening  in  a  dense  irregular  mass.  The  spores  jerk  rapidly  and  the 
peripheral  ones  free  themselves  by  degrees  until  all  get  away.  The 
whole  process  occupies  several  minutes  and  after  the  pressure  is  relieved 
in  the  sporangium  a  good  many  spores  remain  in  the  sporangium  and 
swim  rapidly  there  for  a  good  while,  only  emerging  one  by  one  as  they 
find  the  opening  (apparently  by  chance).  Oogonia  up  to  744  thick;  al¬ 
most  always  elliptical,  the  wall  rather  thick  and  covered  with  protu¬ 
berances  which  show  remarkable  variation  from  low  rounded  warts 
to  long,  sharp  pyramidal  spines.  Eggs  average  334  in  diameter,  usually 
one,  at  times  two  in  an  oogonium  which  they  do  not  quite  fill.  Anther- 
idial  cells  about  184  thick,  varying  little,  elliptical  to  spherical,  much 
smaller  than  the  oogonia,  thin-walled,  smooth;  one,  as  a  rule,  attached  to 
each  oogonium  but  rarely  as  many  as  three;  filled  with  protoplasm  when 
young,  but  empty  when  eggs  are  mature. 

Found  several  times  around  Chapel  Hill  on  A.  imperfecta  and  A. 
flagellata  in  Arboretum  branch. 

Our  plant  agrees  well  with  Fischer’s  description  except  for  the 
thickness  of  the  antheridia  which  in  Fischer’s  plant  is  given  as  28-304. 
In  addition  to  figures  by  Fischer  and  Cornu  cited  above,  see  Petersen 
(To),  fig.  18b. 

In  one  case  material  with  sporangia  covered  with  a  glass  was  watched 
for  half  an  hour.  None  of  the  sporangia  emptied  while  the  cover  was 
on.  The  cover  was  removed  and  almost  instantly  one  of  the  sporangia 
began  shooting  out  its  contents,  the  spores  still  in  the  initial  stages  of 
formation.  The  protoplasm  remained  at  the  sporangial  mouth  and  about 
fifteen  minutes  after  the  sporangium  had  emptied  some  of  the  proto¬ 
plasm  began  to  assume  the  form  of  spores  which  showed  a  rocking  move¬ 
ment.  In  ten  minutes  more  the  entire  mass  had  formed  spores,  many 
of  which  were  breaking  from  the  mass  and  swimming  away.  The  ma¬ 
terial  was  stained  with  iodine  and  two  lateral  cilia  demonstrated  on  the 
spores. 

In  material  stained  with  iodine  and  then  preserved  in  glycerine 
which  contained  a  few  drops  of  eosin  the  sporangia  stained  a  beautiful  red, 


PLATE  62 


PLATE  62 

Olpidiopsis  saprolegniae  var.  levis 

Fig.  I.  Sporangia  causing  gall  in  tip  of  hypha. 

Fig.  2.  Sporangia  sending  tubes  through  wall  of  host. 

Fig.  3.  Two  empty  sporangia  and  one  oogonium  with  an  empty  antheridium. 

Fig.  4.  Several  small  sporangia  in  a  gall. 

Fig.  5.  Oogonia  with  antheridia. 

Fig.  6.  Sporangia  in  hypha  of  a  species  of  Aphanomyces. 

All  figures  X  447,  and  all  from  Saprolegnia  ferax. 

Olpidiopsis  saprolegniae 

Fig.  7.  Oogonia  with  spines. 

Fig.  8.  Oogonia  merely  rough  or  warted. 

Fig.  9.  Spores  with  cilia. 

Fig.  10.  Oogonium  with  antheridium,  and  sporangia  discharging  spores,  all  inside  a  hypha 
of  Achlya  flagellata. 

Figure  9  X  613;  others  X  447. 

Rhizophidium  carpophilum 

Fig.  11.  Sporangia  on  oogonia  of  Achlya  apiculata,  the  lower  one  with  a  short  protrusion 
which  is  about  to  break. 

Fig.  12.  Smaller  sporangia  on  oogonia  of  Achlya  apiculata ,  some  already  discharged,  others 
forming  resting  bodies. 

Fig.  13.  Sporangia  on  oogonia  of  Achlya  apiculata ,  one  of  the  sporangia  in  act  of  giving  off 
spores. 


All  figures  X  670. 


PLATE  62 


OLPIDIOPSIS  SAPROLEGNIAE  VAR.  LEVIS  [FIGS.  1-6] 
OLPIDIOPSIS  SAPROLEGNIAE  [FIGS.  7-10]. 
RHIZOPHIDIUM  CARPOPHILUM  [FIGS.  11-13J. 


OLPIDIOPSIS 


185 


while  the  oogonia  and  the  few  antheridia  which  remained  partly  empty 
were  stained  a  greenish  brown.  This  contrast  readily  enables  one  to 
distinguish  sporangia  from  oogonia. 

Antheridia  in  all  stages  were  observed:  some  full  of  protoplasm 
and  egg  adjoining  not  formed;  some  partly  empty  and  the  egg  beginning 
to  show  a  clear  space  between  itself  and  the  oogonial  wall,  and  some 
entirely  empty  with  the  eggs  formed.  An  antheridium  one-third  empty 
was  watched.  Slowly  the  remainder  of  its  contents  passed  into  the 
oogonium  until  about  one-third  of  the  original  contents  was  left  and 
then  a  cover  glass  was  dropped  on  the  material.  Immediately  after¬ 
wards  part  of  the  contents  of  the  oogonium  shot  back  into  the  anther¬ 
idium,  refilling  it  and  demonstrating  an  open  connection. 

The  oogonial  spines  are  so  hyaline  as  to  be  barely  visible  in  oogonia 
which  have  just  formed  eggs,  but  they  become  much  more  obvious  after 
the  eggs  are  a  day  old.  Young  oogonia  stained  with  iodine  show  spines, 
which  otherwise  would  have  been  overlooked. 

Olpidiopsis  Saprolegniae  var.  levis  n.  var. 

Plate  62,  figs.  1-6 

Sporangia  spherical  to  elliptic,  smooth,  very  variable  in  size  and 
number,  usually  occupying  the  swollen  ends  of  hyphae  but  not  rarely 
also  in  intercalary  swellings;  emptying  by  one  or  two  tubes  which  pene¬ 
trate  the  host’s  wall,  but  go  little  beyond  and  are  usually  short,  at 
times  however  as  long  or  longer  than  the  diameter  of  the  sporangium: 
spores  very  minute  and  numerous,  probably  with  two  cilia,  swimming 
rapidly,  emerging  at  first  through  internal  pressure  and  probably  show¬ 
ing  the  same  sequence  as  described  in  the  preceding  species,  but  not  all 
stages  observed.  Oogonia  elliptic  to  nearly  spherical,  with  the  wall 
rather  thick  and  quite  smooth  and  even ;  antheridial  cells  smaller  than 
the  oogonia,  smooth,  thin-walled,  one  or  two  attached  to  each  oogonium, 
their  contents  usually  disappearing  entirely  by  the  time  the  oogonia 
are  mature. 

Parasitic  on  species  of  Saprolegnia  as  A.  ferax,  S.  nionoica ,  and 
probably  others.  Found  many  times  in  Chapel  Hill,  as  in  the  small 
pond  below  Glen  Burnie  spring,  where  it  may  be  secured  almost  with 
certainty  at  any  time  a  series  of  collections  is  made. 

The  most  important  difference  between  this  plant  and  0.  Saproleg¬ 
niae  is  that  the  oogonia  are  smooth  and  seem  to  average  smaller.  In  the 
latter  they  are  densely  covered  with  warts  or  spines.  This  difference  is 
striking  and  will  make  it  necessary  to  consider  our  plant  a  variety.  1  he 
two  species  of  this  genus  with  smooth  oogonia  that  are  so  far  described 
are  parasitic  on  algae  (see  Fischer,  ’92,  p.  37). 


1 86 


THE  SAPROLEGNIACEAE 


Rhizophidium  carpophilum  (Zopf)  Fischer.  Rabenhorst’s  Krypt.  FI.  1. 
4:  95.  1892.  (2nd.  ed.). 

Rhizidium  carpophilum  Zopf.  Nova.  Acta.  Acad.  Leop.  47:  200, 
pi.  20,  figs.  8-16.  1884. 

Plate  62,  figs.  11-13 

Sporangia  subspherical,  seated  on  the  surface  of  the  oogonia  of  the 
host,  varying  greatly  in  size  and  number,  about  10-30^  in  diameter, 
emptying  through  a  more  or  less  apical,  thin-walled,  short  beak  which 
seems  to  break  and  then  collapse  and  disappear;  spores  very  minute 
and  nearly  hyaline  except  for  one  or  two  dots,  swimming  rapidly.  They 
emerge  singly  and  from  their  own  efforts,  and  dash  around  madly  inside 
the  sporangium  when  the  beak  opens,  seeming  to  find  the  way  out  purely 
by  accident.  It  usually  takes  several  minutes  for  all  to  get  out;  cilia 
number  not  determined  (said  to  be  one).  Sporangia  attached  to  the 
swollen  tip  of  a  mycelial  thread  which  branches  farther  down  and  enters 
the  eggs  of  the  host  and  eventually  destroys  them.  Certain  of  the 
smaller  sporangia  do  not  discharge  at  once,  but  go  into  a  resting  state, 
the  contents  becoming  compacted  into  a  dense  refractive  body. 

Observed  several  times  in  Chapel  Hill,  where  it  is  parasitic  on  the 
oogonia  of  Achlya  apiculata,  A.  flagellata  and  A.  conspicua.  The  eggs  of 
the  host  become  defined,  in  all  cases  we  have  seen,  before  being  dis¬ 
organized,  and  usually  they  are  not  all  attacked,  one  or  several  arriving 
at  healthy  maturity  amid  the  detritus  of  those  destroyed. 

The  present  plant  agrees  well  with  R.  carpophilum  as  described 
and  figured  by  Zopf,  except  that  the  hypha  entering  the  oogonium  is 
thicker  than  he  shows.  Rhizidiomyces  apophysatus  differs  in  the  swell¬ 
ing  just  inside  the  oogonium  wall,  in  the  long  and  more  persistent  empty¬ 
ing  beak  and  in  the  emergence  of  the  spores  in  a  bladder. 

Rhizidiomyces  apophysatus  Zopf.  Nova  Acta  Acad.  Leop.  47:  188.  pi. 

20,  figs.  1-7.  1884. 

Plate  63 

Sporangia  spherical  to  subspherical,  varying  greatly  in  size,  from 
10  to  45;j.  thick;  seated  on  the  surface  of  the  oogonia  of  the  host  and 
communicating  with  the  interior  of  the  oogonia  by  means  of  a  tube¬ 
like  body  which  may  expand  into  an  internal  bladder  (which  may  measure 
as  much  as  1 8 . 5 thick)  from  which  numerous  rhizoid-like  structures 
arise  and  penetrate  the  eggs  or  mingle  with  the  oogonial  contents.  Spore 
initials  appearing  early  and  then  disappearing  by  complete  coalition  to 
reappear  only  after  discharge  into  an  apical  bladder.  Spores  discharged 
somewhat  as  in  Pythium,  the  spore  mass  passing  out  through  a  thin- 
walled  tube,  one  to  three  times  as  long  as  the  diameter  of  the  sporangium, 
which  expands  at  the  tip  into  a  very  delicate  bladder  into  which  the 
spore  mass  flows.  Here  the  spore  initials  gradually  appear  again  and 
complete  their  development.  Before  discharge  they  show  a  distinct 


PLATE  G3 


PLATE  63 


Rhizidiomyces  APOPHYSATUS 
on 

Achlya  conspicua 

Figs.  1-5.  Oogonia  infected  with  the  parasite  to  a  greater  or  less  extent.  In  Fig.  I  the  form¬ 
ation  of  eggs  has  been  prevented  by  an  early  attack.  The  parasite  shows  the 
rhizoidial  rootlets  entering  the  protoplasm  of  the  host,  the  stalk  passing  to 
the  exterior  which  is  often  swollen  to  form  an  apophysis  (a),  and  the  exterior 
swelling  which  becomes  the  sporangium  (b).  All  X  503. 

Fig.  6.  The  same  oogonium  shown  in  Fig.  5  drawn  16  hours  later,  the  sporangium  (b)  now 
full  size  and  showing  the  spore  initials.  X  503. 

Figs.  7-13.  The  same  sporangium  (b)  shown  in  Fig.  6,  with  the  resulting  spores,  the  figures 
drawn  at  intervals  of  about  10  minutes.  The  sac  (c),  in  which  the  spores  are 
emptied,  is  shown  free  in  Fig.  12,  and  fully  developed  spores  in  Fig.  13,  just 
after  the  disappearance  of  the  sac  membrane.  All  X  503. 

Fig.  14.  Two  active  spores  with  a  single  cilium  each.  X  1028. 


PLATE  63 


%,-jm 


RHIZIDIOMYCES  APOPHYSATUS 


RHIZIDIOMYCES 


187 


rocking  motion  which  is  soon  followed  by  the  appearance  of  a  hole 
in  the  bladder  out  of  which  the  spores  rush  rapidly  one  by  one.  Spores 
subspherical,  very  minute,  3 .7^,  with  one  apical  cilium. 

Sexual  reproduction  unknown. 

Recognized  only  twice  at  Chapel  Hill,  and  then  on  oogonia  of  Adilya 
conspicua  collected  from  Arboretum  branch  (No.  7  of  June  29  and  No.  1 
of  July  10). 


BIBLIOGRAPHY 

Agardh,  C.  A.,  ’24:  Systema  Algarum,  p.  47.  Lund,  1824. 

Archer,  Wm.,  ’67:  On  Two  New  Species  in  Saprolegnieae.  Quart.  Jour.  Mic.  Science  7 
N.  S.:  121,  PI.  6.  1867. 

Areschoug,  J.  E.,  ’45 :  Beobachtungen  iiber  die  merkwiirdige  Pilze,  Achlya  prolifera.  Horns- 
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Maurizio,  A.,  ’94:  Zur  Entwickelungsgeschichte  und  Systematik  der  Saprolegnieen.  Flora 
79:  109,  Pis.  3-5.  1894. 

Maurizio,  A.,  ’95:  Zur  Kenntniss  der  Schweizerischen  YVasserpilze  nebst  Angaben  liber 
eine  neue  Chytridine.  Jahresber.  Naturf.  Ges.  Graubundens,  Chur.  38:  9, 
figs.  1-9.  1895. 

Maurizio,  A.,  95a:  Die  YVasserpilze  als  Parasiten  der  Fische.  Zeitschr.  f.  kischerei  u.  deren 
Hilfswissensch.,  3:  270,  figs.  1-7.  1895. 

Maurizio,  A.,  ’96:  Die  Sporangiumanlage  der  Gattung  Saprolegnia.  Jahrb.,  f.  wiss.  Bot. 
29:  75,  Pis.  1-2.  1896. 

Maurizio,  A.,  ’96:  Developpement  des  Saprolegniees  sur  les  grains  de  pollen  dans  1  eau. 
Arch.  Sci.  Phys.  et  Nat.,  Geneve,  S.  4,  2:  599.  1896. 

*  For  similar  work  by  Klebs  on  other  groups  of  plants  see  the  following. 

Ueber  die  Vermehrung  von  Hydrodictyon  utriculatum.  Flora  73:  351.  1890. 

Zur  Physiologie  d.  Fortptianzung  einiger  Pilze  1.  Jahrb  f.  wiss.  Bot.  32:  1.  1898. 

Ueber  Probleme  d.  Entwickelung.  Biol.  Centralblatt.  24:  257,  289,  449,  481,  545,  601.  190-t. 

Ueber  Variationen  der  Bliiten.  Jahrb.  f.  wiss.  Bot.  42:  155,  PI.  8.  1906  [1905]-  (Review  in  Bot.  Gaz.  41.  359- 
1906). 

Ueber  das  Verhaltnis  d.  Aussenwelt  zur  Entwicklung  d.  Pflanzen.  Sitzungsb.  Hcidelb.  Akad.  Wiss.  4,  B,  Abt. 
5,  47  P-  I9I3- 


194 


THE  SAPROLEGNIACEAE 


Maurizio,  A.,  ’96a:  Studien  iiber  Saprolegnieen.  Flora  82:  14,  PI.  1.  1896. 

Maurizio,  A.,  ’96b:  Die  Pilzkrankheit  der  Fische  u.  der  Fischeier.  Zeitschr.  f.  Fischerei  u. 
deren  Hilfswissensch.,  4:  76.  1896. 

Maurizio,  A.,  ’97:  Les  maladies  causees  aux  poissons  et  aux  oeufsde  poissons  par  les  Cham¬ 
pignons.  Rev.  Mycol.  19:  77.  1897. 

Maurizio,  A.,  ’97a:  Die  Pilzkrankheit  der  Fische  und  der  Fischeier.  Centralbl.  f.  Bakt.  u. 
Par.,  1.  Abt.,  22:  408.  1897. 

Maurizio,  A.,  ’98:  Une  methode  pour  evaluer  le  nombre  des  germes  des  Saprolegniees  dans 
l’eau  et  la  vase.  Arch.  Sci.  phys.  et  nat.,  Geneve,  S.  4,  6:  518.  1898. 
Maurizio,  A.,  ’99:  Beitrage  zur  Biologie  der  Saprolegnieen.  Zeitschrift  f.  Fischerei  und  deren 
Hilfswissenschaften.  Mittheil.  des  Deutsch.  Fischerei-Vereins  7,  Heft  2: 
1,  figs.  1-19.  1899.  This  paper  has  been  overlooked  by  subsequent  workers 
in  Europe  as  Minden,  Petersen,  etc.  It  consists  of  four  chapters  and  subjects 
with  a  two-page  preface,  as  follows:  Chap.  I.  Allgemeine  Vegetations- 
bedingungen,  p.  3-13.  Chap.  II.  Verbreitungsmittel  und  das  natfirliche 
Nahrmaterial  der  Saprolegnieen,  p.  14-29.  Chap.  III.  Ueber  eine  Methode, 
um  die  Zahl  der  Keime  der  Saprolegnieen  im  Wasser  zu  bestimmen,  p.  29-42. 
Chap.  IV.  Zur  Morphologie  der  Sporangiumanlage  der  Gattung  Saprolegnia; 
Beschreibung  neuer  Arten;  abnorme  Bildungen  und  Parasiten,  p.  42-66. 
This  last  describes  many  new  species  and  forms,  all  of  which  we  have  noted. 
Meyen,  F.  J.  F.,  ’31:  Zur  Erlatiterung  des  Vorhergehenden.  p.  381,  Pis.  78,  80.  (Appended 
to  Nees  v.  Esenbeck,  ’31). 

Meyen,  F.  J.  F.,  ’35:  Einige  nachtragliche  Bemerkungen  fiber  die  Pilzbildung  auf  den 
Leibern  d.  abgestorbenen  Fliegen.  Wiegmann’s  Archiv  f.  Naturgesch.  1. 
Jahrg.  2:  354.  1835. 

Meyer,  Arthur,  ’04:  Orientirende  Untersuchungen  fiber  Verbreitung,  Morphologie  und 
Chemie  des  Volutins.  Bot.  Zeit.  62:  113,  PI.  15.  1904. 

Minden,  von,  ’02:  Ueber  Saprolegniineen.  Centralbl.  Bakt.,  8,  abt.  2:  805,  821.  1902. 
Minden,  von.  ’12:  Saprolegniineae.  Kryptogamen  Flora  Mark  Brandenburg  6:  479,  figs. 

i-2e  on  p.  520,  figs.  3-8  on  p.  556,  figs.  I2-I5d  on  p.  580,  figs.  9-1 1  on  p. 
590.  1912.  Also  on  p.  609,  which  appeared  in  1915. 

Miyoshi,  M.,  ’94:  Ueber  Chemotropismus  d.  Pilze.  Bot.  Zeit.  62:  1.  1894. 

Mficke,  M.,  ’08:  Zur  Kenntnis  d.  Eientwicklung  und  Befruchtung  von  Achlya  polyandra 
de  Bary.  Ber.  d.  Deutsch.  Bot.  Gesell.  26a:  367,  PI.  6.  1908. 

M filler,  P.  E.,  ’68:  Bidrag  til  Cladocerernes  Forplantningshistorie.  Naturh.  Tidsskrift 
Reihe  3,  5:  296.  1868—69. 

M filler,  C.,  ’83:  Meine  Stellung  zur  Frage  von  den  Spermamoeben  der  Saprolegnieen.  Bot. 
Centralblatt.  15:  125.  1883. 

M filler,  Fritz,  Ti:  Untersuchungen  fiber  die  chemotaktische  Reizbarkeit  der  Zoosporen 
von  Chytridiaceen  und  Saprolegniaceen.  Jahrb.  f.  wiss.  Bot.  49:  421. 
1911. 

Murray,  G.,  ’85:  Notes  on  the  Inoculation  of  Fishes  with  Saprolegnia  ferax.  Jour.  Bot. 
23:  302.  1885. 

Naegeli,  C.,  ’46:  Zellenbildung  und  Zellenwachsthum  bei  den  Pflanzen.  Zeit.  f.  wiss.  Bot. 

1:  34,  Pis.  1-2;  3:  22,  Pis.  3-4.  1844-46. 

Nees  v.  Esenbeck,  C.  G.,  ’23:  Zusatz.  (Appended  to  Carus,  ’23,  p.  507). 

Nees  v.  Esenbeck,  C.  G.,  ’31:  Mittheilungen  aus  der  Pflanzenwelt.  II.  Confervenbildung 
aus  todten  Fliegenleibern.  Nova  Acta  Acad.  C.  L.  C.  N.  C.  15,  Th.  2: 
374-  1831. 


BIBLIOGRAPHY 


195 


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Pieters,  A.  J.,  ’15b:  The  Relation  between  Vegetative  Vigor  and  Reproduction  in  Some 
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Ramsbottom,  J.,  T6:  A  List  of  the  British  Species  of  Phycomycetes,  etc.,  with  a  Key  to  the 
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Ramsbottom,  J.,  T6a:  Notes  on  the  List  of  British  Phycomycetes.  Trans.  Brit.  Myc.  Soc. 
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196  THE  SAPROLEGNIACEAE 

Reinke,  J.,  ’69:  Ueber  die  Geschlechtsverhaltnisse  von  Saprolegnia  monoica.  Archiv  f. 
mic.  anatomie  von.  M.  Schultze.  5:  183,  PI.  12.  1869. 

Reinsch,  P.  F.,  ’78:  Beobachtungen  iiber  einige  neue  Saprolegnieae ,  etc.  Jahrb.  f.  wiss. 
Bot.  11:  283,  Pis.  14-17.  1878. 

Ricker,  P.  L.,  ’02:  Preliminary  List  of  Maine  Fungi.  University  of  Maine  Studies.  No.  3: 
19.  1902. 

Robin,  C.,  ’53:  Histoire  naturelle  des  Vegetaux  parasites,  etc.  Paris,  1853. 

Robinson,  E.  M.,  ’96:  [Fungus  and  parasites  on  salmon  fry].  Rep.  U.  S.  Fish  Com.  1894, 
p.  60.  1896  [Letter  to  T.  H.  Bean]. 

Rothert,  \V., ’88:  Die  Entwicklung  d.  Sporangien  bei  den  Saprolegnieen.  Cohn’s  Beitrage 
zur  Biologie  d.  Pflanzen.  5:  291,  PI.  10.  1892  [1890].  Distributed  in  1888. 

Also  published  in  Polish  in  Sitzungsb.  (Rozpr.)  Krakau.  Akad.  Math.-Naturw. 
Classe  17:  1.  1887. 

Rothert,  W.,  ’94:  Ueber  das  Schicksai  d.  Cilien  bei  den  Zoosporen  d.  Phycomyceten. 

Berichte  d.  Deutsch.  Bot.  Gesell.  12:  268,  PI.  20.  1894. 

Rothert,  W.,  ’03:  Die  Sporenentwicklung  bei  Aphanomyces.  Flora  92:  293,  figs.  1-7.  1903. 
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Rudolph,  K.,  ’12:  Chondriosomen  und  Chromatophoren.  Ber.  d.  Deutsch.  Bot.  Gesell. 
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Ryder,  John  A.,  ’82:  On  the  Retardation  of  the  Ova  of  the  Shad  ( Alosa  Sapidissima), 
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1:  177.  1882.  Also  appearing  with  very  slight  changes  in  Fish  Commis¬ 
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Ryder,  John  A.,  ’83:  Cause  of  the  Non-Development  of  Fungus  on  the  Eggs  Hatched  in 
the  McDonald  Jar.  Bull.  U.  S.  Fish  Com.  2:  188.  1883. 

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Schmitz,  F.,  ’79:  Untersuchungen  fiber  die  Zellkerne  d.  Thallophyten.  Verh.  des  nat. 

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Trow,  A.  H.,  ’04:  On  Fertilization  in  the  Saprolegnieae.  Ann.  Bot.  18:  541,  Pis.  34-36. 
1904. 

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Unger,  F.,  ’43:  Einiges  zur  Lebensgeschichte  d.  Achlya  prolifera.  Linnaea  17:  129,  PI. 

4.  1843.  Also  in  Ann.  Sci.  Nat.  Bot.  Ser.  3,  2:  5,  PI.  1.  1844. 

Vincent,  Eugene,  To:  Causes  of  Disease  in  Young  Salmonoids.  Bull.  Bureau  Fisheries 
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Walz,  J.,  ’70:  Beitrage  zur  Kenntniss  d.  Saprolegnieen.  Bot.  Zeit.  28:  537  and  553,  PI.  9. 
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Weatherwax,  P.,  ’14:  Aphanomyces  phycophilus.  Proc.  Indiana  Acad.  Sci.,  1913,  p.  109, 
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INDEX 


Achlya,  i,  2,  3,  4,5,  6,  7,  9,  10,  17,  88,  90,  91, 
95,  96,  164,166,  183;  key  to  the  species, 
98 

americana,  5,  97,  99,  101,  111,  117,119, 
120,  142,  147 

americana  var.  cambrica,  1,95,  97,  99,  1 3 1 , 

139 

apiculata,  4,  13,  14,  100,  102,  123,  127, 
128,  129,  186 

apiculata  var.  prolifica,  4,  100,  102,  124, 

127 

aplanes,  6,  58,  98,  99,  101,  117,  143 
asterophora,  139 
Braunii,  76,  77,  78 

caroliniana,  5,  6,  7,  14,  98,  100,  101,  122 
colorata,  5,  6,  14,  86,  98,  102,  103,  107, 
108,  134,  139 

conspicua,  4,  97,  100,  101,  113,  117,  131, 
186,  187 
contorta,  147 
cornuta,  99,  101,  110 
deBaryana,  1,  5,  6,  95,  96,  97,  98,  99, 
101,  112,  1 1 7,  132,  141 
deBaryana  var.  americana,  112. 
deBaryana  var.  intermedia,  118,  1 19,  142 
decorata,  139 
dioica,  no,  147 
dubia,  4,  6,  100,  101,  135,  149 
flagellata,  4,  6,  7,  13,  14,  97,  98,  99,  101, 

116,  1 19,  165,  184,  186 
glomerata,  6,  14,  96,  100,  102,  133 
gracilipes,  100,  129,  130,  132,  142 
Hoferi,  98,  101,  145 
hypogyna,  7,  14,  65,  93,  102,  103 
imperfecta,  9,  92,  97,  98,  99,  101,  112,  115, 

117,  118,  122,  143,  184 
intermedia,  49,  50 

Klebsiana,  7,  9,  98,  99,  101,  120,  133 
leucosperma,  146 
lignicola,  6,  106,  107 
megasperma,  100,  101,  128 
Nowickii,  147 

oblongata,  100,  101,  113,  132 
oblongata  var.  globosa,  100,  101,  133 
ocellata,  147 
oidifera,  147 

oligacantha,  100,  102,  144,  145,  146 
Orion,  4,  95,  98,  99,  101 ,  112,  165 
papillosa,  99,  102,  109 
paradoxa,  4,  82,  90,  91,  93,  96 
penetrans,  147 

polyandra  de  Bary,  6,  9,  96,  97,  98,  112, 

1 1 7,  119-  HO  I42 

polyandra  forma  Americana,  97,  112 
polyandra  Hildebrand,  1,  3,  .5,  6,  41,  95, 

100,  101 ,  1 13,  120,  129,  131,  132,  141, 
142,  145 

prolifera,  6,  40,  58,  96,  98,  99,  101,  118, 
120,  143,  144,  146 

proliferoides,  7,  13,  14,  96,  97,  98,  99, 

101,  115,  11 7,  1 1 8,  119,  144 
racemosa,  2,  5,  6,  14,  65,  66,  81,  98,  101, 

103,  106,  108,  109,  1 13,  134 


Achlya 

racemosa  var.  stelligera,  107,  108 
radiosa,  98,  102,  107,  134,  139 
recurva,  100,  102,  109,  144 
spinosa,  99,  102,  107,  hi,  134,  138 
stellata,  no,  in,  139 
Treleaseana,  79 
sp.,  100,  137,  148,  165 

Achlya  parasitized  by  Aphanomyces,  164,  165 
Achlyogeton  solatium,  167 
Alga,  blue-green,  parasitic  on  Saprolegnia,  36 
Allomyces,  16,  180,  181 
arbuscula,  182 

Aphanomyces,  I,  2,  3,  5,  14,  15,  17,  96,  160, 
183;  key  to  the  species,  160 
coniger,  161,  166,  168 
helicoides,  160,  168 

laevis,  1,  160,  161,  163,  164,  166,  167,  168, 
169 

norvegicus,  161,  166,  168 
parasitica,  15,  1 61 ,  165 
phycophilus,  161,  166,  167 
scaber,  161,  163,  164,  166 
stellatus,  7,  65,  161,  163,  166,  167,  168 
Aplanes,  17,  76 

androgynus,  24,  76,  77,  80,  132 
Braunii,  77,  78 
Treleaseanus,  25,  61,  79,  132 
Apodachlya,  12,  169,  172  key  to  the  species, 
172 

brachynema,  169,  170,  172,  173 
brachynema  var.  major,  170,  174 
completa,  170,  172 
punctata,  172,  173,  174 
pyrifera,  7,  169,  172,  173,  174 
pyrifera  var.  macrosporangia,  169 
Apodya  brachynema,  173 
lactea,  76,  170 
Araiospora,  2 
pulchra,  170 
spinosa,  170 

Bacillus  piscicidus  bipolaris,  59 
salmonis  pestis,  59 
Blastocladia,  180,  182 

Pringsheimii,  181,  182 
prolifera,  181,  182 
ramosa,  181,  182 
rostrata,  181,  182 
strangulata,  181,  182 
Blastocladiaceae,  16,  180 

Centroachlya,  96,  98 

Desmids,  161 
Diatoms,  161 
Diblepharis,  179 
fasciculata,  180 
insignis,  180 

Dictyuchus,  5,  10,  17,  91,  150,  key  to  the  spe¬ 
cies,  151 

carpophorus,  1 5 1 ,  157 
clavatus,  148 
Magnusii,  15 1 ,  153,  154 


199 


200 


INDEX 


Dictyuchus 

monosporus,  7,  151,  152,  153,  155,  156,  157 
polysporus,  151,  152,  153,  157 
sterile,  7,  14,  150,  151 
Diplanes  saprolegnioides,  49,  50 

Egg  structure,  10 
Empusa,  75 
Euachlya,  103 
Eumonoblepharis,  179 
Eusaprolegnia,  23 
Exoospora,  179 

Fish,  growth  on  dead,  133 

growth  on  live,  8,  9,  13,  58,  59,  145,  146 
growth  on  eggs,  62,  74,  75,  139 

Glomeroachlya,  100 
Gonapodya,  179 

polymorpha,  169 
siliquaeformis,  169 

Isoachlya,  7,  17,  25,  72,  81,  90,  91;  key  to  the 
species,  82 
eccentrica,  82,  87 
monilifera,  14,  24,  82,  83,  88 
paradoxa,  91 

toruloides,  25,  67,  82,  86,  89 
unispora,  82,  85,  87,  88 

Leptodora  Kindtii,  158 
Leptolegnia,  2,  3,  4,  16,  17,  157 
caudata,  13,  14,  158 
Leptomitaceae,  16,  169,  179 
Leptomitus,  12,  15,  170 
brachynema,  173 
lacteus,  7,  14,  59,  169,  170 

Minobranchus,  59 
Monoblepharidaceae,  16,  178 
Monoblepharis,  179 
brachyandra,  179 
lateralis,  179 
macrandra,  7,  179 
ovigera,  179 
polymorpha,  179,  183 
potymorpha  var.  macrandra,  179 
prolifera,  75 
regignens,  179 
sphaerica,  179 
Mougeotia,  168 
Myriablepharis,  178 
Myxonema,  59 

Naegelia,  170,  177 
Naegeliella,  170 

Oedogonium,  167 
Olpidiopsis,  1 1 7 
echinata,  183 
index,  183 
major,  183,  184 
Saprolegniae,  183,  184,  185 
Saprolegniae  var.  levis,  185 
Olpidium  Borzianum,  183 

Parasites  of  the  Watermolds,  36,  80,  ii“,  132, 
164,  183 


Parasitic  Watermolds,  13 
Achlya  Hoferi,  145 
Aphanomyces,  160 
Aphanomyces  laevis,  161 
Aphanomyces  norvegicus,  168 
Aphanomyces  parasitica,  165 
Aphanomyces  phycophilus,  167 
Aphanomyces  stellatus,  163 
Leptolegnia  caudata,  158 
Saprolegnia  parasitica,  57 
Periodicity  Table,  14 
Peronosporaceae,  147,  162 
Pleolpidium  Monoblepharidis,  I  S3 
Rhipidii,  183 

Protoachlya,  4,  7,  17,  82,  90,  96 
paradoxa,  14,  91,  102 
Pseudolpidium  aphanomyces,  183 
fusiforme,  183 
Saprolegniae,  183 
Pseudosaprolegnia,  24 
Pythiopsis,  17;  key  to  the  species,  18 
cymosa,  10,  12.  14,  18,  20,  21,  80,  86 
Humphreyana,  14,  18,  20,  86 
Pythium,  2,  75,  178 
deBaryanum,  75 

Rheosporangium,  178 
Rhipidium,  2 

americanum,  170 
continuum,  170 
interruptum,  170 
spinosum,  183 

Rhizidiomyces  apophysatus,  183,  186 
Rhizidium  carpophilum,  186 
Rhizophidium  carpophilum,  183,  186 
Rozella  septigena,  183 
simulans,  183 

Saprolegnia,  1,  8,  9,  10,  11,  12,  22,  103,  183, 
185;  key  to  the  species,  23 
androgyna,  77,  78 

anisospora,  23,  25,  27,  30,  31,  33,  84 
anisospora  form  B,  36 
asterophora,  8,  24,  64,  134,  164 
bodanica,  40,  42,  73,  82,  86 
Candida,  76 
corcagiensis,  76 
crustosa,  68 

crustosa  var.  I,  23,  25,  69 
crustosa  var.  II,  23,  25,  69 
crustosa  var.  Ill,  23,  25,  70 
curvata,  23,  24.  72,  82 
deBaryi,  75 

delica,  23,  25,  27,  30,  35,  47,  48,  84 
diclina,  I,  14,  22,  23,  25,  26,  29,  31,  35, 
.43,  48,  59,  70,  71,  84 
dioica  deBary,  26,  69,  70,  71,  74 
dioica  Pringsheim,  26,  40,  49 
dioica  Schroeter,  26,  46,  49 
dioica  var.  racemosa,  40 
elongata,  76 

esocina,  23,  26,  40,  41,  73 
ferax,  8,  14,  22,  23,  25,  27,  40,  43,  46,  47, 
48,  49,  51,  58,  59,  66,  73,  84,  183 
ferax  forms  1  and  2,  41 
floccosa,  23,  26,  52,  74 
furcata,  8,  23,  25,  72 
heterandra,  46,  49 


INDEX 


201 


Saprolegnia 

hypogyna,  24,  25,  46,  60,  77,  80,  93,  103, 
183 

hypogyna  var.  Coregoni,  61,  62 
hypogyna  var.  Coregoni  var.  I-V,  61,  62 
intermedia,  60,  61,  62 
Kauffmaniana,  23,  25,  29,  35 
lapponica,  23,  26,  42,  73 
Libertiae,  76 

litoralis,  24,  25,  54,  56,  57,  75,  77 
megasperma,  24,  25,  56 
minor,  75 

mixta,  1,  22,  23,  26,  41,  42,  46,  54,  72,  84 
mixta  var.  Asplundii,  23,  26,  74 
monilifera,  68,  82,  86,  88 
monoica,  1,  8,  9,  14,  22,  24,  25,  43,  46,  48, 
49,  51, 52,  54-  55-  58,  59-  63,  71, 72, 73, 75 
monoica  var.  glomerata,  24,  25,  49,  51,  75 
monoica  var.  montana,  24,  25,  75 
monoica  var.  turfosa,  79,  80,  81 
monoica  var.  vexans,  24,  25,  53 
mucophaga,  76 

paradoxa  Maurizio,  24,  55,  75,  79 
paradoxa  Petersen,  75,  79,  80 
parasitica,  9,  23,  24,  57 
philomukes,  76 
quisquiliarum,  76 
racemosa  var.  spinosa,  139 
retorta,  55,  71 

rhaetica,  24,  25,  67,  68,  82,  84 
saccata,  76 
Schachtii,  75 


Saprolegnia 

semidioica,  31,  49,  50 
siliquaeformis,  75 
spiralis,  23,  25,  55,  71 
stagnalis,  23,  25,  70 
tenuis,  76 

Thureti,  40,  41,  42,  46,  72,  73 
torulosa,  8,  9,  24,  25,  63,  67,  68,  82,  83. 

84,  86 

Treleaseana,  76,  77,  79,  81 
turfosa,  79,  80 
variabilis,  24,  25,  67,  82,  84 
xylophila,  75 
sp.,  8;  58,  64,  76,  79,  80 
Saprolegniaceae,  1,  10, 12,  16;  key  to  the  genera, 

l7  . 

Saprolegniales,  15;  key  to  the  families,  16 
Sapromyces,  176 

androgynus,  170 
elongatus,  170 
Reinschii,  169,  170,  176 
Septocladia  dichotoma,  182 
Spirogyra,  129,  167,  168 

Thraustoachlya,  100 
Thraustotheca,  10,  17,  148 
clavata,  7,  14,  136,  148 
Vampyrellidium  vagans,  132 

Woronina  polycystis,  183 

Zygnema,  167,  168 


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